DETROIT -

It's a simple fact: our bodies were made to move.

When the human body does not stay active is assumes something is wrong.

"Being inactive is really a disease state. So, if you're not moving your body at all, you're not getting any physical activity, you are in, essentially, a state of decline," said Dr. Susan Joy, of the Cleveland Clinic Sports Health.

However, you don't have to run marathons to reap the rewards. A new study by the National Institutes of Health suggests even low levels of physical activity can add years to your life.

Researchers found people who got the recommended amount of exercise lived nearly three and 1/2 years longer than those who did not. Even people who got only 1/2 that amount of exercise added nearly two years to his or her life.

"You get a more substantial gain taking the sedentary people to low levels of activity than the moderately fit to more fit," said Joy.

So how much exercise is enough?

It is recommended everyone age 18 to 64 gets 2 and 1/2 hours of moderate exercise each week or 1 and 1/2 hours of vigorous exercise.

"We all need a little bit of physical activity. If you're not sure what your true exercise needs are for your goals, whether it's for hypertension, cardiac disease, for lowering your cancer risk, for managing your weight, for dealing with stress, that's worth talking to your doctor about because sometimes one type of exercise might help you get closer along to your goals than another," Joy said.

Health experts say, in this case, some exercise really is better than none at all. One study found regular, brisk walking can reduce the risk of a heart attack by the same amount as jogging.