Children and adolescents should do an hour or more of moderate-intensity to vigorous aerobic physical activity each day. Vigorous physical activity should be done at least three days out of the week and it should include running, jumping rope, skipping, playing hopscotch and muscle-strengthening activities such as tug of war, modified sit-ups and push-ups.

For adults, the U.S. Department of Health and Human Services recommends 2 1/2 hours of moderate-intensity aerobic physical activity a week. That should include walking briskly, water aerobics, ballroom dancing or gardening. They can also choose to do an hour and 15 minutes of vigorous activity such as running, swimming laps, or hiking uphill with a heavy back pack. The exercises can be done with free weights or machines, resistance bands, calisthenics that use body weight for resistance (push-ups, pull-ups, sit-ups), or carrying heavy loads or doing heavy gardening such as digging or hoeing.

Adults with disabilities should follow the regular adult guidelines if they can. If not, they can choose some physical activity suited to their abilities.

Older Americans should follow the guidelines for other adults if they are able. If not, they should be as active as their physical condition allows.

For healthy pregnant women the guidelines recommend at least 2.5 hours of moderate exercise during pregnancy and the postpartum period.

The exercising guidelines were developed after extensive studies, which showed that 60% of adults don’t exercise enough, and 25% do not exercise at all. To prevent the development of serious ailments like cancer, osteoporosis, diabetes, Alzheimer’s, heart disease, depression, exercising from an early age is crucial.

“The more physically active you are, the more health benefits you gain,” HHS Secretary Michael Leavitt concluded.