2 1/2 hours of moderate-intensity aerobic activity per week
and muscle-strengthening activities two or more days a week.
OR
One hour and 15 minutes of vigorous-intensity aerobic activity per week
and muscle-strengthening activities two or more times a week.
OR
A combination of both. As a rule of thumb, one minute of
vigorous activity equals two minutes of moderate activity.
Muscle-strengthening activities should target the arms, legs and trunk. It is best to spread out your aerobic activity during the week, but you should exercise for at least 10 minutes at a time. A 10-minute brisk walk three times a day, five days a week will give you a total of 2½ hours of moderate-intensity activity.
Source: 2008 Physical Activity Guidelines for Americans,
U.S. Department of Health and Human Services.
