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Why exercise helps mental health
Exercise affects mental health through multiple simultaneous mechanisms. In the short term, physical activity reduces circulating stress hormones including cortisol and adrenaline, releases endorphins and endocannabinoids that improve mood and reduce pain perception, and increases blood flow to the prefrontal cortex (the part of the brain most responsible for clear thinking and emotional regulation). These effects are present even after a single session, which is why many people report feeling calmer or more optimistic immediately after exercise despite having started with low motivation.
Over the long term, regular exercise supports neuroplasticity (the brain's ability to form new connections and adapt to experience). Aerobic exercise in particular promotes the production of brain-derived neurotrophic factor (BDNF), a protein that supports the growth and maintenance of neurons and has been consistently associated with lower rates of depression. This is one reason regular exercisers tend to recover from stressful periods faster and report higher baseline resilience than sedentary people with otherwise similar circumstances.
Sleep quality, self-efficacy, and social connection are additional pathways through which exercise supports mental health. People who exercise regularly tend to sleep better, which in turn improves mood and cognitive function. The process of setting and achieving exercise goals (however modest) builds a sense of competence that generalises to other areas of life. And activities done in social contexts, from team sports to walking with a friend, add a relational dimension to the benefit that solo exercise cannot provide.
