Get a minimum of 2-1/2 hours per week of moderate-intensity aerobic activity, or a minimum of 1-1/4 hours per week of vigorous-intensity aerobic activity, or a combination of the two. That could mean a brisk walk for 30 minutes a day, five days a week; a high-intensity spinning class one day for 45 minutes, plus a half hour jog another day; or some other combination of moderate and vigorous activity. Doubling the amount of activity (5 hours moderate- or 2-1/2 hours vigorous-intensity aerobic activity) provides even more health benefits. Adults should also aim to do muscle-strengthening activities at least two days a week.