Physical activity need not be strenuous to achieve health benefits.

Men and women of all ages benefit from a moderate amount of daily physical activity. The same moderate amount of activity can be obtained in longer sessions of moderately intense activities (such as 30 minutes of brisk walking) as in shorter sessions of more strenuous activities (such as 15-20 minutes of jogging).

Additional health benefits can be gained through greater amounts of physical activity. Adults who maintain a regular routine of physical activity that is of longer duration or of greater intensity are likely to derive greater benefit. However, because risk of injury also increases with greater amounts of activity, care should be taken to avoid excessive amounts.

Previously sedentary people who begin physical activity programs should start with short sessions (5-10 minutes) of physical activity and gradually build up to the desired level of activity.

Adults with chronic health problems, such as heart disease, diabetes, or obesity, or who are at high risk for these conditions should first consult a physician before beginning a new program of physical activity. Men over age 40 and women over age 50 who plan to begin a new program of vigorous activity should consult a physician to be sure they do not have heart disease or other health problems.