When you're having fun doing leisure-time physical activities, you can lose all track of time. But don't fret: It may yield as much as four more years for you.

The National Institutes of Health tracked lifestyle patterns of 650,000 Americans ages 40 and older and found that those who participated in the government's recommended amount of moderate physical activity -- 21/2 hours a week -- lived 3.4 years longer than those who didn't exercise. Those who participated in twice the recommended amount lived 4.2 years longer. The NIH found that even those who aren't in good physical shape added years as long as they exercised, even if they didn't get the recommended weekly amount.

advertisement | advertise on newsday

Among the leisure activities that provide a moderate physical workout are brisk walking, bicycling, gardening and dancing.

To download the government's Physical Activity Guidelines for Americans, go to bit.ly/pag2008.