HEALTH 100: Introduction to Health and Wellness

Sources and References

Primary textbook — Insel, Roth, Irwin, Burke, Core Concepts in Health, 4th Canadian ed. (McGraw-Hill). Supplementary texts — Rebecca J. Donatelle Health: The Basics; Matthew Walker Why We Sleep; Kelly McGonigal The Upside of Stress; BJ Fogg Tiny Habits. Online resources — Canada’s Food Guide (food-guide.canada.ca); Canadian 24-Hour Movement Guidelines (CSEP); World Health Organization fact sheets; Centers for Disease Control and Prevention public health resources.

Chapter 1 — Defining Health and Wellness

Health used to mean the absence of disease. A century of research has expanded the idea. The WHO’s 1948 definition calls health “a state of complete physical, mental and social well-being, and not merely the absence of disease or infirmity.” Canadian public health literature layers on a life-course perspective: health at age twenty is already the product of genes, early childhood, neighbourhood, and accumulated behaviours, and the habits built now shape risk for decades.

Two related terms help. Health is a relatively objective state — how body and mind function, how resistant you are to illness, how long you are likely to live. Wellness is the active process of moving toward your best possible state given your circumstances. A person with chronic illness can still pursue high wellness; a person with excellent biomarkers can still live poorly.

Most introductory courses organize wellness into interlocking dimensions. The six classic dimensions are physical, emotional, intellectual, social, spiritual, and occupational, with environmental added as a seventh in recent Canadian editions. Physical wellness covers fitness, nutrition, sleep, and avoidance of harmful substances. Emotional wellness is the capacity to recognize and regulate feelings. Intellectual wellness is lifelong curiosity and mental engagement. Social wellness is the quality of one’s relationships and support network. Spiritual wellness is a sense of meaning and values, religious or secular. Occupational wellness is satisfaction and growth through work or study. Environmental wellness is the realization that health depends on the air, water, food systems, and communities around us. These dimensions trade off in real life — an all-nighter trades physical rest for intellectual output — and the goal is a sustainable balance rather than perfection in each.

The determinants of health framework shifts attention outward. Public Health Agency of Canada lists twelve determinants, including income and social status, employment and working conditions, education and literacy, childhood experiences, physical environments, social supports and coping skills, healthy behaviours, access to health services, biology and genetic endowment, gender, culture, and race and racism. Research suggests that medical care accounts for a surprisingly small share of population health outcomes — perhaps ten to twenty percent — with behaviours, social circumstances, and environment doing much of the rest. This is why a course on personal wellness still has to talk about neighbourhoods, wages, and food systems.

A useful framework for personal change is the Health Belief Model, which predicts action when a person perceives a real threat, believes the behaviour will help, can do it, and meets a cue to action. Alongside it sits self-efficacy — Bandura’s term for confidence in executing a specific behaviour — the best behavioural predictor in most wellness studies, built through small successes, watching similar peers succeed, encouragement, and managing arousal.

Chapter 2 — Human Anatomy and Physiology: A Quick Tour

Wellness choices land on a body whose systems were shaped by evolution to move daily, eat intermittently, socialize, and sleep deeply. A whirlwind tour makes that plain.

The cardiovascular system is a closed circuit driven by a four-chambered heart. The right side pumps deoxygenated blood to the lungs; the left side pumps oxygenated blood to every tissue. Arteries carry blood away under high pressure; veins return it under low pressure with help from one-way valves and skeletal-muscle pumping; capillaries, one cell thick, are where gases and nutrients exchange. Blood pressure is reported as systolic (peak during contraction) over diastolic (resting), with healthy adult values near 120/80 mmHg.

The respiratory system moves air from nose and mouth through trachea, bronchi, and bronchioles into alveoli wrapped in capillaries, where gas exchange follows partial-pressure gradients, driven by the diaphragm and intercostal muscles.

The musculoskeletal system supplies structure, leverage, and movement. Skeletal muscle contracts through sarcomeres whose actin and myosin filaments slide past each other; tendons transmit force to bone and ligaments stabilize joints.

The nervous system splits into the central nervous system (brain and spinal cord) and the peripheral nervous system, which includes somatic nerves and the autonomic branch. The autonomic branch has sympathetic (“fight or flight”) and parasympathetic (“rest and digest”) arms, which we will meet again in the chapter on stress.

The endocrine system uses hormones to regulate growth, metabolism, reproduction, and stress, via the hypothalamus, pituitary, thyroid, adrenals, pancreas, and gonads. The digestive system breaks food down in mouth and stomach, absorbs in the small intestine, and recovers water in the large intestine; the gut microbiome influences immunity, mood, and metabolism. The immune system combines innate defenses (skin, inflammation, phagocytes) with adaptive B and T lymphocytes that generate specific antibodies and memory. The urinary, reproductive, integumentary, and lymphatic systems round out the picture. Every wellness decision — a meal, a workout, a night of sleep, a stressful conversation — cascades across all of these systems. You are not treating parts; you are tuning a whole.

Chapter 3 — Physical Activity and Cardiovascular Fitness

Physical activity is any bodily movement that raises energy expenditure above rest; exercise is structured, repeated activity aimed at improving fitness. Cardiorespiratory fitness — the capacity of the heart, lungs, and blood to deliver oxygen to working muscles — is arguably the single most powerful predictor of early mortality in adults. A low score on a treadmill or step test is associated with risk comparable to smoking.

The Canadian 24-Hour Movement Guidelines, published by the Canadian Society for Exercise Physiology, recommend that adults aged 18 to 64 accumulate at least 150 minutes of moderate-to-vigorous aerobic activity per week, in bouts of ten minutes or more, plus muscle-strengthening activities on two or more days, and several hours of light movement. They also emphasize limiting sedentary time and breaking up long sitting bouts, and getting seven to nine hours of sleep. The guidelines are explicit that any movement counts and that replacing sitting with light activity already helps.

Aerobic training adapts the body in several durable ways. The heart’s left ventricle enlarges and pumps more blood per beat (higher stroke volume), so resting heart rate falls. Capillary density in trained muscles increases, mitochondria multiply and grow, and enzymes of oxidative metabolism upregulate. VO2 max — the maximum rate at which the body can use oxygen — rises, typically 15 to 25 percent in previously sedentary people over a few months of consistent work. Triglycerides fall, HDL cholesterol rises, insulin sensitivity improves, blood pressure drops a few mmHg on average, and mood lifts.

The principles of training are worth memorizing because they apply to every mode, from running to lifting to yoga. Overload says that to gain, you must stress the system beyond normal demand. Progression says that overload must increase gradually as the body adapts. Specificity says adaptations match the stimulus: swimmers get good at swimming. Reversibility says detraining is real — stop for a few weeks and some gains fade. Individuality says genetics, age, and history mean responses vary. The FITT prescription formalizes overload: Frequency (how often), Intensity (how hard), Time (how long), and Type (what activity).

Intensity is often set by heart rate. A simple estimate of maximum heart rate is 220 minus age; moderate intensity is 64 to 76 percent of that, vigorous is 77 to 93 percent. The talk test is the practical version: moderate means you can talk but not sing; vigorous means you can say only a few words at a time. For aerobic beginners, starting with brisk walking, stationary cycling, swimming, or elliptical training at moderate intensity three to five days per week for 20 to 30 minutes, then progressing volume before intensity, is the classic template. Interval training, alternating short bouts at high intensity with easier recovery, produces similar VO2 max gains in less time for people who can tolerate the strain.

A proper warm-up — five to ten minutes of easy movement that rehearses the upcoming activity — raises muscle temperature, widens small vessels, and primes the nervous system. A cool-down helps return heart rate and blood pressure toward baseline and reduces post-exercise dizziness. Hydration and environmental awareness (heat, humidity, cold, air quality) round out safety.

Chapter 4 — Resistance Training, Flexibility, and Injury Prevention

Cardio is only half of physical fitness. The other half — muscular strength, muscular endurance, flexibility, and body composition — needs its own attention.

Resistance training builds strength by forcing muscle fibres to adapt to loads above their habitual range. In the first several weeks, most gains come from neural adaptations: the nervous system learns to recruit more motor units, fire them more synchronously, and inhibit antagonists less. After that, hypertrophy — growth of existing muscle fibres through added contractile proteins — carries the bulk of progress. Beginners of almost any age respond, and older adults may benefit most because sarcopenia, the age-related loss of muscle mass and power, is one of the strongest predictors of frailty, falls, and loss of independence.

A workable beginner program follows a few rules. Train each major muscle group two or three times per week. Choose six to ten compound movements that cover the whole body — squat, hinge, push, pull, carry, core — and perform two to four sets of eight to fifteen repetitions, leaving one or two reps in reserve at first. Rest 60 to 180 seconds between sets depending on goal. Increase weight, reps, or sets slowly (progressive overload) while keeping form crisp. Bodyweight, resistance bands, free weights, and machines all work; what matters is consistent stimulus above habit.

Strength training also strengthens bones. Mechanical loading triggers osteoblasts to lay down new bone, improving density and reducing the lifetime risk of osteoporotic fracture. This effect is strongest when loading is novel, high-impact, or multidirectional, which is why resistance plus weight-bearing cardio is the gold standard.

Flexibility — the range of motion around a joint — is trained by stretching. Static stretching (holding a position for 15 to 60 seconds) is useful after a workout or as its own session; dynamic stretching (controlled movements through range) works better as a warm-up because heavy static stretching immediately before power output can slightly reduce performance. Yoga and mobility routines combine flexibility with balance, and balance training is a proven way to cut fall risk.

Body composition — the ratio of fat mass to lean mass — matters more than body weight. Two people at the same weight and height can have very different health profiles depending on how much is muscle, how much is fat, and where the fat is stored. Visceral fat around abdominal organs is more metabolically active and more dangerous than subcutaneous fat on hips and thighs.

Injury prevention rests on a handful of habits. Progress load no faster than roughly ten percent per week. Balance opposing muscles so pushing and pulling, hip-dominant and quad-dominant movements all get work. Respect pain: sharp, pinpoint, or joint-centred pain is a warning; dull muscle soreness 24 to 48 hours after a new workout (delayed-onset muscle soreness) is normal. If an acute injury happens, the modern version of RICE is PEACE and LOVE — Protect, Elevate, Avoid anti-inflammatories early, Compress, Educate; then Load, Optimism, Vascularization, Exercise. Use footwear and equipment appropriate to the activity, and plan in recovery days.

Chapter 5 — Nutrition Fundamentals: Macronutrients and Micronutrients

Nutrition is the science of how food provides energy and building blocks for the body. Six classes of nutrients matter: carbohydrates, proteins, fats, vitamins, minerals, and water. The first three supply energy and are called macronutrients because we need them in gram quantities; vitamins and minerals are micronutrients needed in milligrams or micrograms.

Carbohydrates provide about four kilocalories per gram and are the body’s preferred fuel for high-intensity activity and the brain. Simple carbohydrates — glucose, fructose, sucrose, lactose — occur in fruit, milk, and added sugars. Complex carbohydrates are starches and fibres found in grains, legumes, tubers, and vegetables. Fibre resists digestion and does important work anyway: soluble fibre (oats, beans, psyllium) slows glucose absorption and lowers LDL cholesterol; insoluble fibre (wheat bran, vegetable skins) adds bulk and speeds transit. Adult women need about 25 g of fibre per day, men about 38 g, and most North Americans fall well short. The glycemic index ranks foods by how rapidly they raise blood glucose; the practical version is simple: whole, minimally processed carbohydrates with fibre or fat alongside protein will blunt glucose spikes.

Proteins also provide about four kilocalories per gram but are mainly used to build and repair tissue, enzymes, and hormones. Proteins are made of 20 amino acids, nine of which are essential because the body cannot synthesize them. Animal foods (meat, fish, dairy, eggs) are complete proteins; most plant foods are low in one or two amino acids but a varied plant diet easily covers all nine. Adult requirements are about 0.8 grams of protein per kilogram of body weight for sedentary people and 1.2 to 2.0 g/kg for those training hard or trying to preserve lean mass while losing fat.

Fats provide nine kilocalories per gram, the densest energy source, and supply essential fatty acids, fat-soluble vitamins, and membrane material. Unsaturated fats — monounsaturated (olive oil, avocado, most nuts) and polyunsaturated (fatty fish, flax, walnuts, sunflower) — lower cardiovascular risk when they replace saturated fats. Saturated fats (red meat, butter, coconut oil) raise LDL cholesterol in most people and should be limited but not eliminated. Trans fats, industrial byproducts of partial hydrogenation, are the worst actors and are effectively banned in Canadian food manufacturing. Omega-3 fatty acids (EPA and DHA from fish; ALA from plants) have anti-inflammatory and cardiovascular benefits.

Vitamins are organic compounds needed in tiny amounts. Fat-soluble vitamins (A, D, E, K) are stored in body fat and can accumulate to toxic levels from supplements; water-soluble vitamins (B complex and C) are mostly excreted when in excess. Vitamin D is a standout in Canada because skin synthesis from sunlight drops to near zero in winter at northern latitudes; Health Canada recommends that adults consider 400 to 1000 IU of supplemental vitamin D during the winter months, more for older adults.

Minerals are inorganic elements. Macrominerals (calcium, phosphorus, potassium, sodium, magnesium, chloride, sulphur) are needed in hundreds of milligrams or more; trace minerals (iron, zinc, copper, selenium, iodine, chromium, fluoride, manganese, molybdenum) in smaller amounts. Iron deficiency is the most common nutrient deficiency worldwide, especially in menstruating women and vegetarians. Calcium and vitamin D together support bone health. Sodium intake is too high in most Canadian diets, contributing to hypertension; the adequate intake is about 1500 mg per day, with an upper limit near 2300 mg.

Water is the overlooked nutrient. Adults need roughly 2.5 to 3.5 L of total water per day from food and drink combined, more in heat and exercise. Thirst is a decent but delayed signal; urine colour is the simplest day-to-day check — pale yellow is the target.

Chapter 6 — Energy Balance and Healthy Eating Patterns

Total daily energy expenditure is the sum of basal metabolic rate (the energy needed to keep you alive at rest, typically 60 to 75 percent of the total), the thermic effect of food (about 10 percent, the cost of digesting and absorbing nutrients), and activity energy expenditure (the rest, from exercise and non-exercise movement). When intake equals expenditure, weight stays stable; a positive balance adds mass, a negative balance reduces it. The simple arithmetic hides enormous complexity — hormones, sleep, stress, palatability of food, and gut signals all shape how hungry or full you feel — but in the long run, energy balance still governs body composition.

The 2019 redesign of Canada’s Food Guide abandoned the old food-group rainbow in favour of a plate image. Fill half the plate with vegetables and fruit, one quarter with whole grains, and one quarter with protein foods, with water as the drink of choice and encouragement to choose plant-based proteins often. The guide also emphasizes the how of eating: cook more meals at home, be mindful of eating habits, eat meals with others, use food labels, and limit foods high in sodium, sugars, or saturated fat. Ultra-processed foods — industrial formulations of refined starches, sugars, fats, and additives — are associated in large prospective studies with higher rates of obesity, type 2 diabetes, and cardiovascular disease, and the guide nudges toward whole foods without forbidding anything.

Well-studied dietary patterns converge on similar advice. The Mediterranean pattern features vegetables, fruit, legumes, nuts, whole grains, olive oil, fish, moderate dairy, and limited red meat; it has the strongest randomized-trial evidence for cardiovascular prevention. The DASH pattern (Dietary Approaches to Stop Hypertension) is similar with lower sodium and has the strongest evidence for lowering blood pressure. Plant-forward patterns, including vegetarian and vegan, are compatible with excellent health when attention is paid to vitamin B12, iron, zinc, omega-3s, calcium, and vitamin D.

Reading a Nutrition Facts label takes a minute and saves decades. Start with the serving size, because everything on the label is per serving. Look at calories to set context. Use the % Daily Value column as a quick gauge — 5 percent or less is “a little,” 15 percent or more is “a lot.” Aim high on fibre, vitamins, and minerals; aim low on sodium, saturated fat, and added sugars. The ingredient list is ordered by weight, so if the first ingredient is sugar, you are mostly buying sugar.

Eating behaviour matters as much as macronutrients. Hunger and fullness cues are reliable when you slow down enough to hear them. Distracted eating, screen eating, and eating from packages blur the signal. Mindful eating — noticing taste, texture, and satiety — is a low-cost intervention with real effects on intake. A practical template for a balanced meal is the plate method: vegetables, a palm-sized protein, a fist-sized serving of whole grains or starchy vegetable, and a thumb-sized serving of healthy fat.

Disordered eating and clinical eating disorders — anorexia nervosa, bulimia nervosa, binge-eating disorder, avoidant/restrictive food intake disorder — are serious medical conditions, not choices or phases. Early warning signs include rigid food rules, secrecy, purging, extreme weight changes, excessive exercise tied to eating, and preoccupation with food. Canadian campus counselling and Health Services departments can help students find treatment; early care improves outcomes significantly.

Chapter 7 — Sexual Health and Reproductive Wellness

The WHO defines sexual health as “a state of physical, emotional, mental and social well-being in relation to sexuality; it is not merely the absence of disease, dysfunction or infirmity.” That means sexual wellness includes safety, consent, respect, pleasure, and the ability to make informed choices — not just avoiding infection and unwanted pregnancy.

Consent is the foundation. Consent is specific to each activity, voluntary, informed, enthusiastic, ongoing, and reversible. Silence, intoxication, sleep, pressure, or a prior “yes” are not consent. Canadian criminal law treats consent as affirmative and contemporaneous, and post-secondary sexual violence policies across the country reflect this. Building a culture of consent means checking in verbally, respecting “no” and “I’m not sure” equally, and recognizing that power imbalances (age, authority, intoxication, dependency) can make true consent impossible.

Sexually transmitted infections include bacterial (chlamydia, gonorrhoea, syphilis), viral (HIV, HPV, herpes simplex, hepatitis B and C), parasitic (trichomoniasis, pubic lice), and fungal infections. Many are asymptomatic for long periods, which is why regular screening matters for anyone sexually active with new or multiple partners. Key Canadian points: chlamydia is the most commonly reported STI, with rates especially high in people aged 15 to 24; HPV is the most common viral STI and is the cause of nearly all cervical cancers and many oropharyngeal and anal cancers, and the HPV vaccine (Gardasil 9) provides durable protection and is publicly funded for school-aged youth in every province; HIV remains a serious infection but is now manageable with daily antiretroviral therapy, and people with an undetectable viral load cannot transmit HIV sexually (U=U); pre-exposure prophylaxis (PrEP) is a daily or on-demand medication that dramatically reduces HIV risk for people at elevated exposure.

Prevention layers work together. External and internal condoms are the only methods that reduce both pregnancy and STI transmission. Dental dams reduce oral transmission. Routine STI screening (usually urine and swab tests, with blood draws for syphilis, HIV, and hepatitis) is recommended annually for sexually active young adults and more often with new partners. Vaccination against HPV and hepatitis B is standard in Canada.

Contraception options fall into categories by effectiveness as typically used. Long-acting reversible contraception (LARC) — IUDs (hormonal or copper) and the implant — is the most effective reversible method at over 99 percent, because it does not rely on daily action. Hormonal methods requiring user action (pill, patch, ring, injection) are about 91 to 94 percent effective with typical use, mostly because of missed doses. Barrier methods (external condoms, diaphragms) are around 82 to 88 percent effective with typical use. Fertility awareness, withdrawal, and spermicide alone are less reliable. Emergency contraception — levonorgestrel (Plan B) up to 72 hours or ulipristal up to 120 hours after unprotected intercourse, or a copper IUD up to five days — can prevent pregnancy after the fact and is available without prescription in Canada.

Reproductive wellness also means being comfortable with your own anatomy, recognizing changes (lumps, persistent pain, unusual discharge, changes in menstrual patterns), and seeking care early. Body literacy reduces shame and improves outcomes. Understanding the menstrual cycle as a whole-body rhythm — hormonal fluctuations affecting mood, sleep, energy, and appetite — helps people plan around their own physiology rather than fighting it.

Sexual orientation and gender identity are dimensions of wellness, not diagnoses. Inclusive care, community, and policy are public-health issues: 2SLGBTQ+ people face higher rates of depression, anxiety, and substance use largely because of minority stress (stigma, rejection, discrimination), and those outcomes improve with social acceptance, affirming care, and legal protection.

Chapter 8 — Social Health and Relationships

We are obligate social mammals. Decades of research show that strong social connection is as strongly associated with longevity as smoking, and more strongly than obesity or inactivity. A landmark meta-analysis by Julianne Holt-Lunstad and colleagues found that people with stronger social relationships had a 50 percent higher likelihood of survival over a given period than those with weaker ties. Loneliness and social isolation are now treated as public-health problems in their own right.

Social support comes in several flavours. Emotional support is the presence of someone who listens without judgement. Instrumental support is practical help — a ride, a meal, money. Informational support is advice, knowledge, or feedback. Appraisal support is constructive evaluation of how you are doing. Healthy people tend to have at least a few sources of each, often in different relationships.

Relationships develop through stages, from acquaintance to friendship to close friendship to intimacy. Self-disclosure — sharing personal information — deepens bonds when it is reciprocal, appropriate to the stage, and honest. Active listening — full attention, reflecting back, asking questions without advice — is the single most trainable relationship skill. Conflict is inevitable in any close relationship; healthy conflict uses “I” statements, stays focused on the issue, avoids contempt and stonewalling, and aims for repair rather than victory. John Gottman’s research identifies four “horsemen” that predict relationship breakdown: criticism of the person rather than the behaviour, contempt, defensiveness, and stonewalling. Their antidotes are gentle start-up, culture of appreciation, taking responsibility, and self-soothing.

Healthy relationships of every kind — family, friendship, romantic, workplace — share features: mutual respect, honest communication, fair distribution of effort and emotional labour, support for each other’s growth, and the freedom to disagree and repair. Unhealthy patterns include jealousy escalating to control, isolation from other supports, belittling or name-calling, financial control, and any physical or sexual coercion. Intimate partner violence is a leading cause of injury for women in Canada; campus wellness resources and the national 24-hour line (1-866-863-0511 in Ontario, similar in every province) provide support.

The social determinants of health revisit the idea from chapter 1 through the social lens. Income, stable housing, safe neighbourhoods, food security, employment, education, social inclusion, and freedom from discrimination are not just nice-to-haves — they are causal inputs to physical and mental health. A campus is a temporary social environment, and joining clubs, volunteering, study groups, and residence communities is not extracurricular fluff; it is health infrastructure.

Chapter 9 — Brain Health and Cognitive Wellness

The brain consumes about 20 percent of resting energy in a body that is about 2 percent brain by weight, a clue to how much is going on up there. Its roughly 86 billion neurons form trillions of synapses, and they remain capable of change throughout life. Neuroplasticity is the umbrella term for the brain’s ability to rewire in response to experience. Synapses strengthen with repetition and prune with disuse; new neurons are born in the hippocampus throughout adult life; white matter reorganizes around learned skills.

Several behaviours directly protect cognitive function. Aerobic exercise raises brain-derived neurotrophic factor (BDNF), a growth factor that supports neuron survival, synapse formation, and learning. Sleep consolidates memory and clears metabolic waste, including beta-amyloid, through the glymphatic system. Learning new, effortful skills — a language, an instrument, a sport — builds cognitive reserve, the buffer that keeps people functioning despite age-related changes. Social engagement protects against cognitive decline, likely through the combination of emotion regulation, novelty, and exercise. Diet matters: the MIND diet (a hybrid of Mediterranean and DASH) is associated with lower rates of Alzheimer’s dementia.

Mental wellness overlaps with but is not the same as absence of mental illness. Positive mental health includes emotional well-being, life satisfaction, purpose, and the capacity to cope with stress. Mental illness includes mood disorders (major depressive disorder, bipolar disorder), anxiety disorders (generalized anxiety, social anxiety, panic, phobias), obsessive-compulsive and related disorders, trauma and stressor-related disorders (PTSD), eating disorders, and substance use disorders, among others. About one in five Canadians will experience a mental illness in any given year; by age 40 about half of Canadians will have had one. Treatment works: evidence-based psychotherapies (cognitive behavioural therapy, interpersonal therapy, dialectical behaviour therapy, acceptance and commitment therapy) and pharmacotherapy are effective for most conditions, usually most powerful in combination.

Building emotional regulation skills is part of brain health. Naming emotions accurately (affect labelling) reduces their intensity in the amygdala. Cognitive reappraisal — reframing a situation — is more sustainable than suppression, which tends to backfire. Mindfulness meditation, practised even briefly, can reduce rumination and improve attention. Psychological flexibility — the ability to stay present, hold thoughts lightly, and act in line with values — is a common target across modern therapies.

Help-seeking is itself a brain-health skill. If a mood, anxiety, or substance problem is interfering with studies, sleep, relationships, or functioning for more than two weeks, it warrants a conversation with a professional. University health services, family doctors, walk-in clinics, the Here24/7 line, Kids Help Phone (up to age 29), and 9-8-8 (Canada’s suicide crisis helpline) are all accessible entry points.

Chapter 10 — Stress, the HPA Axis, and Coping

Stress is the body’s response to any demand. The term covers a biochemistry, a psychology, and an everyday feeling all at once. A small amount of stress is helpful — it organizes attention and mobilizes energy. Chronic, unmanaged stress is one of the most important modifiable risk factors for cardiovascular disease, depression, anxiety disorders, and immune dysfunction.

The physiology has two overlapping pathways. The fast track is the sympathoadrenal medullary (SAM) axis: the sympathetic nervous system fires, the adrenal medulla releases adrenaline and noradrenaline within seconds, heart rate and blood pressure rise, digestion slows, and you are ready to fight or flee. The slower track is the hypothalamic-pituitary-adrenal (HPA) axis: the hypothalamus releases CRH, the pituitary releases ACTH, the adrenal cortex releases cortisol, which raises blood glucose, suppresses non-essential systems, and keeps you mobilized. Cortisol normally follows a daily rhythm — high in the morning, low at night — and feeds back to shut off the axis when the threat passes. Chronic stress blunts the rhythm and leaves cortisol dysregulated. Hans Selye’s General Adaptation Syndrome — alarm, resistance, exhaustion — captures the arc, and prolonged cortisol contributes to abdominal fat, insulin resistance, hypertension, impaired memory, immune suppression, and mood problems.

Kelly McGonigal’s The Upside of Stress reframes this usefully. What strongly predicts health outcomes is mindset about stress and the social context around it. People who view stress as an energizing challenge tend to respond with a “challenge” physiology, and worse health effects are blunted; people who view stress as always toxic tend to pay more health costs. Framing matters and can be trained.

Coping splits into problem-focused (changing the situation — planning, problem-solving) and emotion-focused (changing the response — relaxation, reframing, support-seeking, acceptance). Match strategy to situation: problem-focused when you have control, emotion-focused when you do not. Evidence-based tools include regular aerobic exercise (the most researched and effective), breathing practices with long exhales (4-7-8, box breathing, coherent breathing at around six breaths per minute), progressive muscle relaxation, Jon Kabat-Zinn’s mindfulness-based stress reduction (MBSR), cognitive restructuring of catastrophic thinking, time in nature, social connection, and adequate sleep.

Burnout, in the WHO classification as an occupational phenomenon, has three dimensions: emotional exhaustion, cynicism or depersonalization, and reduced sense of accomplishment. Students get it from chronic academic overload plus disconnection from purpose, and recovery requires not just rest but renegotiation of workload, meaning, and relationships.

Chapter 11 — Sleep: Architecture, Function, and Hygiene

Sleep is not down-time. It is active, structured, and essential. Matthew Walker’s Why We Sleep delivers a blunt summary of the research: shortchanging sleep damages nearly every measurable aspect of health.

An adult night cycles through two kinds of sleep about every 90 minutes. Non-REM sleep has three stages, from light N1 through N2 to the deepest N3, or slow-wave sleep, dominated by high-amplitude delta waves. REM sleep — rapid eye movement sleep — is paradoxically more brain-active than some waking states, with vivid dreaming and muscle paralysis. Slow-wave sleep dominates early cycles and REM dominates later ones, which is why cutting sleep short especially costs REM.

Each stage does specific work. Slow-wave sleep is when the glymphatic system flushes metabolic waste, growth hormone pulses, and declarative memories consolidate from hippocampus into cortex. REM integrates emotional memories and forms creative associations. The consensus requirement for adults is seven to nine hours per night, with very narrow individual variation — only a tiny fraction of people genuinely thrive on less than six. Chronic restriction of even a couple of hours per night accumulates performance deficits comparable to legal intoxication within two weeks, while the sleeper usually feels fine. Shortfalls are associated with higher risk of obesity, type 2 diabetes, cardiovascular disease, depression, anxiety, impaired immunity, accidents, and poorer learning.

Sleep is governed by two parallel systems. Circadian rhythm, a ~24-hour clock in the suprachiasmatic nucleus, is entrained mainly by morning light and suppressed by evening light. Homeostatic sleep pressure builds with time awake, largely through adenosine accumulation, and dissipates with sleep. Caffeine works by blocking adenosine receptors — it does not remove adenosine, just hides it — which is why a late-afternoon coffee (half-life five to six hours) wrecks sleep even when you fall asleep on time.

Sleep hygiene lets these systems do their job. Keep a consistent bedtime and wake time, within an hour on weekends. Get bright outdoor light in the first hour of waking to anchor the clock. Dim lights and screens in the evening to protect melatonin. Keep the bedroom cool (18 to 20 °C), dark, and quiet. Reserve the bed for sleep and sex. Avoid heavy meals, alcohol, and nicotine close to bedtime; alcohol sedates but fragments sleep and suppresses REM. If you cannot fall asleep after twenty minutes, get up and do something quiet in dim light until sleepy. Common disorders include insomnia, obstructive sleep apnea (repeated airway collapse, often with snoring — a major cardiovascular risk), restless legs syndrome, and circadian rhythm disorders. Cognitive behavioural therapy for insomnia (CBT-I) is first-line for chronic insomnia and beats sleep medications in head-to-head trials; sleep apnea is treated with CPAP and lifestyle change.

Chapter 12 — Chronic Disease: Prevention and Management

Chronic non-communicable diseases account for about two-thirds of deaths in Canada and the majority of healthcare costs. Four categories drive most of the burden: cardiovascular disease, cancer, chronic respiratory disease, and diabetes. Four risk behaviours — tobacco use, physical inactivity, unhealthy diet, and harmful alcohol use — drive most of those diseases. The arithmetic is uncomfortable and hopeful at the same time: most chronic disease is preventable.

Cardiovascular disease (CVD) includes coronary artery disease, stroke, heart failure, and peripheral artery disease. Atherosclerosis — the slow build-up of fatty plaques in arteries — is the common pathway; plaques narrow vessels and can rupture, triggering clots that cause heart attacks and strokes. Modifiable risk factors include hypertension, high LDL cholesterol, tobacco, diabetes, obesity, inactivity, poor diet, excessive alcohol, chronic stress, and poor sleep. Heart attack warnings include chest pain or pressure, radiating pain, shortness of breath, nausea, and cold sweat; women often present atypically. Stroke warnings follow FAST: Face drooping, Arm weakness, Speech difficulty, Time to call emergency services.

Cancer is hundreds of diseases sharing the feature of cells growing out of control. Major modifiable risk factors include tobacco, alcohol (Canadian guidance now notes no amount is risk-free), obesity and inactivity, UV exposure, HPV, and H. pylori. Screening — Pap or HPV tests for cervical, fecal tests or colonoscopy for colorectal, mammography for breast — catches disease early when treatment works best, and self-awareness (reporting persistent changes in skin, breasts, or testes) complements formal screening.

Diabetes comes in two main forms. Type 1 is autoimmune destruction of insulin-producing beta cells, requiring lifelong insulin. Type 2 combines insulin resistance with progressive beta-cell decline and is strongly tied to excess weight, inactivity, poor diet, sleep loss, and chronic stress. The Diabetes Prevention Program trial showed roughly a 58 percent risk reduction from lifestyle change — modest weight loss, 150 weekly activity minutes, whole-food diet — beating metformin. Complications include cardiovascular and kidney disease, retinopathy, neuropathy, and non-healing wounds. Chronic respiratory diseases (COPD, asthma) link heavily to tobacco, air pollution, allergens, and irritants. Smoking cessation remains the single most effective intervention in chronic disease medicine: quit at any age and risk drops, with much of the cardiovascular benefit appearing within a year or two.

The prevention toolkit across all chronic disease is shorter than people expect. Do not smoke or vape. Move most days. Eat a whole-food, mostly plant diet. Sleep seven to nine hours. Manage stress. Limit alcohol (the lower, the better). Get routine screening appropriate for age and sex. Stay up to date on vaccinations, including annual flu shots and COVID-19 boosters as recommended. Know your numbers — blood pressure, lipids, fasting glucose or A1c, waist circumference. See a primary care provider regularly. None of this is glamorous; all of it works.

Living with chronic disease is itself a wellness domain. Self-management — understanding the condition, taking medications, monitoring symptoms, adjusting activity, communicating with clinicians — predicts outcomes almost as powerfully as the treatment plan itself. Chronic disease does not preclude high wellness; it reshapes the route to it.

Chapter 13 — Environmental Determinants of Health

Individual behaviour happens inside an environment. The air you breathe, the water you drink, the food system you depend on, the climate you live in, the buildings you sit in, and the communities you move through all shape your health — sometimes invisibly, sometimes dramatically.

Air quality affects respiratory and cardiovascular health at exposures well below levels that smell bad. Particulate matter (PM2.5), ozone, and nitrogen oxides all contribute. Canadian wildfire smoke, increasingly common, can push urban air far above baseline; the Air Quality Health Index (AQHI) gives daily guidance. Indoor air matters just as much — gas cooking, poorly vented heating, indoor smoking, and off-gassing materials degrade the air where people spend most of their time. Carbon monoxide detectors and radon testing (radon is the leading cause of lung cancer in non-smokers) are cheap and worth doing. Water quality is generally excellent in Canadian municipalities, but lead service lines in older homes and long-standing boil-water advisories in many First Nations communities show that access is not universal.

Climate change is a health issue — framed by the Lancet Countdown and WHO as the greatest health threat of the 21st century. Rising temperatures drive heat-related illness and death, especially in older adults. Longer wildfire seasons worsen air quality and mental health. Changing precipitation affects food and water security. Expanding tick ranges push Lyme disease further into Canada. Flooding damages housing and displaces communities, and climate anxiety and post-disaster PTSD are increasingly documented.

Food systems, built environments, and workplaces connect environment to daily health. Industrial food supply shapes what is affordable and available; food deserts and food swamps are real. Walkable neighbourhoods, cycling infrastructure, parks, transit, and mixed-use zoning correlate with higher physical activity, better mental health, and lower rates of chronic disease; car-dependent sprawl is a risk factor you inhabit. Occupational hazards — noise, chemicals, ergonomic strain, shift work, psychosocial stress — contribute meaningfully to chronic disease, and knowing your rights under health and safety legislation is part of wellness literacy. The same behaviours that protect personal health (walk, cycle, eat more plants, waste less) generally also reduce environmental impact: health and sustainability are two windows on the same system.

Chapter 14 — Behaviour Change: Models and Practical Strategies

Knowing what to do is easier than doing it. The gap between intention and action is where behaviour change science lives, and the good news is that the gap is smaller than it looks when the right tools are used.

The Transtheoretical Model (Stages of Change) from Prochaska and DiClemente describes behaviour change as a process moving through stages. Precontemplation: no intention to change in the next six months. Contemplation: seriously thinking about changing within six months, often ambivalent. Preparation: intending to act within a month and taking initial steps. Action: actively modifying the behaviour for less than six months. Maintenance: sustaining it for more than six months, with work focused on preventing relapse. Termination (added later): the new behaviour is so established that relapse is unlikely. Relapse is not a separate stage but a normal event — most people cycle through stages several times before a lasting change. The useful intervention depends on the stage: precontemplators need information, contemplators need decisional balance (weighing pros and cons), and people in action need skills, environmental change, and social support.

Motivational Interviewing (William Miller and Stephen Rollnick) is a conversational approach for contemplation and preparation. Its spirit is partnership, acceptance, compassion, and evocation — drawing out the person’s own motivations rather than imposing arguments. Core skills are OARS: Open-ended questions, Affirmations, Reflections, Summaries. It avoids the righting reflex — the urge to correct or lecture — which typically increases resistance, and has strong evidence in substance use, exercise, diet, and adherence. Self-Determination Theory (Deci and Ryan) adds that behaviours stick when they satisfy three needs: autonomy, competence, and relatedness. Interventions that respect these outperform those built on pressure, guilt, or shame.

Habit science complements the stages. A habit is a behaviour automatized through repetition in a stable context. The classic cue-routine-reward loop describes how context triggers the routine and the reward reinforces it; over time, the cue pulls the routine automatically. This is why environment design beats willpower. BJ Fogg’s Tiny Habits adds a practical recipe: anchor a tiny new behaviour to an existing routine, make it small enough to feel silly (“floss one tooth”), and celebrate immediately to lock in the reward. James Clear’s Atomic Habits emphasizes making desired behaviours obvious, attractive, easy, and satisfying.

Implementation intentions are one of the most reliable tricks in behavioural science. A goal intention is “I will exercise more”; an implementation intention is “When it is 5:00 p.m. on a weekday, I will put on my running clothes and run the riverside loop.” Specifying when, where, and how roughly doubles follow-through. SMART goals — specific, measurable, achievable, relevant, time-bound — work best when paired with short process goals (what you will do this week) alongside outcome goals, with simple tracking for feedback and accountability.

Relapse prevention is a skill, not a failure mode. Anticipate high-risk situations (stress, travel, social pressure, illness), rehearse responses in advance, distinguish a lapse from a full relapse, and resume the plan quickly. Marlatt’s model points out that attribution after a lapse matters: “I am weak” predicts full relapse, while “I slipped under unusual conditions” predicts quick recovery. Social and environmental leverage amplifies everything — tell people what you are doing, change the environment so the healthy choice is the easy one (fruit on the counter, runners by the door, phone out of the bedroom), and join a group that already lives the behaviour.

Approach yourself the way a decent coach approaches a talented beginner: high expectations, patient timelines, honest feedback, warmth. Perfectionism predicts dropout; self-compassion, in Kristin Neff’s research, predicts persistence and recovery from setbacks. This course is really a course in self-leadership across decades, and its content — anatomy, activity guidelines, food patterns, sleep windows, stress tools, relationship skills, screening schedules, environmental awareness, behaviour change models — is the map. You are the one walking. The work of the next ten, twenty, forty years is not to do all of this at once but to assess honestly where you are, install the next small upgrade until it runs on its own, and choose the next. Stacked over a life course, those small upgrades compound into the difference between a life that happens to you and a life you are actively living.