Physical activity is now considered a major modifiable factor for preventing and reducing the mortality from cardiovascular disease, diabetes and some cancers, as well as improving musculoskeletal and mental health. Increasing epidemiological evidence confirms the health benefits of moderate regular physical activity. A dose response relationship remains, with greater benefits derived from increased intensity and duration of physical activity. Clinicians and exercise scientists should consider physical inactivity as important a risk factor as hypertension or elevated serum cholesterol levels. The broader public health objectives are to measure and monitor physical activity levels among all Australians, and to develop interventions to increase regular participation for the whole population. Population Campaigns and behaviour change programs are needed to increase the prevalence of participation in physical activity.