The rate of overweight and obesity is increasing worldwide, with significant impact on health. Obesity is a risk factor for morbidity and mortality, and weight loss should take a multi-pronged approach, including dietary control and physical activity. The lack of physical activity, sedentary behaviour, and poor cardiorespiratory fitness are all independent risk factors for morbidity and mortality, thus it is important to advise lifestyle changes to address these issues. Most individuals who have no contraindications can embark on light- to moderate-intensity physical activity without the need for medical clearance. Specific advice on physical activity should be given, targeting the individual, and this can be done using the FITT (frequency, intensity, time, type) principle. Physical activity should also be reviewed regularly and progressed gradually to target physical activity guidelines. Individuals should also be encouraged to replace sedentary behaviour with at least light-intensity physical activity whenever possible.