Introduction

The physical, mental, cognitive, and health benefits of regular physical activity, exercise and sport participation are today well documented. Regular exercise positively influences most of our physiological systems and helps in protecting against, and rehabilitation of, several chronic diseases including cardiovascular disease, numerous cancers, diabetes, stroke, and metabolic disorders (e.g., obesity). It also builds muscle and strengthens bones, preventing osteoporosis. In the elderly, it helps in maintaining balance, thereby reducing the risk of falls and maintaining independent living. This is particularly important as falls and related injuries are the leading cause of mortality and morbidity in people aged 65 years and older. Exercise also helps to alleviate symptoms of anxiety and depression and buffers against stress. Moreover, there is good evidence to suggest that regular exercise maintains brain integrity and improves cognitive functioning across the lifespan. It has been suggested that, if exercise could be packed into a pill, it would be the single most widely prescribed and beneficial medicine. Regular exercise appears to be a ‘magic bullet’ for human health and well-being.

Physical inactivity or sedentary behaviour, on the other hand, is also an important cause of health problems in Western societies. The amount of sedentary behaviour we engage in on a daily basis (e.g., watching television, surfing the internet, reading, or playing videogames), independent of how much physical activity or exercise we do, predicts ill health. For instance, a large longitudinal Canadian study showed that those who sat a very long time in one block had a 50 per cent increase in mortality in comparison to those who sat for shorter periods in one block. This study showed a dose–response relationship (positive correlation) between sitting time (duration of blocks) and ill health, which was independent of the amount of physical activity people engaged in (Katzmarzyk, Church, Craig, and Bouchard, 2009). This suggests that the time we spend sitting and its distribution across the day is related to morbidity and mortality, independent of being less or more physically active. This is why many governments across the globe have developed campaigns to promote physical activity, exercise, and sports. In this chapter, we will demonstrate that social psychologists can contribute in important ways to reach these goals.