In view of the global surge in obesity and non-communicable diseases, such as cardiovascular conditions, diabetes and cancer, there is an urgent need to promote population-level health. Globally, physical inactivity is a leading risk factor for non-communicable diseases and mortality and carries a considerable public health burden. The health benefits of physical activity are well established. Regular exercise of moderate intensity reduces the risk of chronic diseases and is an effective means of extending both lifespan and years lived in good health. Participation in sports therefore plays a key role in maintaining public health and reducing the burden of non-communicable diseases and the associated increase in the rate of premature deaths. Furthermore, physical activity and sport offer a promising avenue for the promotion of mental health across the lifespan. Appropriate lifestyle changes in regard to physical activity will eventually help shift the population distribution of risk and aid in preventing non-communicable diseases. Robust scientific evidence demonstrates that physical activity and sport can play an important role in assisting in the prevention and management of chronic diseases at the individual and population levels and in alleviating the economic and human cost of disease. The combined expertise of medicine, exercise science and sports should therefore guide the training of doctors, encouraging them to incorporate physical exercise into their daily practice. However, science can only enhance the common good if its significance is appreciated by policymakers and the public and its implementation leads to improvements in health. Those with power to implement change must act on the evidence provided by science.