If exercise could be packaged into a pill, it would be the most prescribed medication in human history — and almost certainly the greatest pharmaceutical breakthrough ever achieved. Regular moderate-to-vigorous physical activity touches virtually every organ system in the body.

• It prevents or softens the blow of the most prevalent and costly diseases of modern life:
• Cardiovascular disease, type 2 diabetes, several cancers, depression, anxiety, dementia, and osteoporosis.
• At the same time, it improves cognitive function, emotional wellbeing, sleep quality, sexual health, and longevity in ways no drug has ever managed to replicate.

The fact that most adults in developed nations can’t even meet relatively modest public health guidelines for physical activity is, by any honest measure, one of the greatest preventable health crises of our time.

The cardiovascular benefits of exercise are among the most thoroughly documented findings in all of medical science. Regular aerobic exercise lowers resting heart rate, improves how much blood the heart pumps with each beat, reduces blood pressure, cuts triglycerides and LDL cholesterol, raises HDL cholesterol, improves insulin sensitivity, dampens systemic inflammation, and even spurs the growth of new blood vessels — a process known as angiogenesis.

Taken together, these changes reduce the risk of heart attack and stroke by around thirty-five percent in active adults compared to sedentary ones. That’s an effect size that beats most medications prescribed specifically to reduce cardiovascular risk.

What exercise does to the brain is equally remarkable, and for a long time, far less appreciated. Regular aerobic activity promotes neurogenesis — the creation of new neurons — in the hippocampus, the brain region most critical to learning and memory. It raises levels of brain-derived neurotrophic factor, a protein often described as fertiliser for the brain, which helps neurons survive, encourages new synaptic connections, and appears to offer real protection against the neurodegeneration that underlies Alzheimer’s disease and other dementias. Meta-analyses of randomised controlled trials have found that exercise produces effects on depression comparable to antidepressant medications — with better long-term results and none of the side effects that cause so many patients to quietly stop taking their prescriptions.

Strength training, for years overshadowed by cardio in public health messaging, is now recognised as just as essential — especially as we get older. Muscle mass starts declining around age thirty. Without deliberate resistance training, adults lose between three and eight percent of muscle per decade, a process called sarcopenia that accelerates sharply after sixty and is closely tied to falls, fractures, metabolic problems, and loss of independence. Regular resistance training preserves and builds muscle, improves insulin sensitivity and glucose metabolism, strengthens bones, lowers the risk of metabolic syndrome, and appears to cut all-cause mortality risk even when you account for cardiovascular fitness. Combining aerobic exercise with resistance training produces greater benefits than either one does alone.

The amount of exercise needed to make a real difference is also more achievable than many people think. Walking for thirty minutes five days a week, cycling to work, taking the stairs, standing during phone calls — all of these are associated with meaningful improvements in health outcomes. Exercise doesn’t need to be punishing to be worthwhile. The evidence is clear on this. The most important step is simply moving from complete inactivity to moderate movement, and the best way to make that stick is to find something you actually enjoy doing.