Vigorous workouts could extend life.

If you walk your dog, work in the garden, go bowling, or do projects around the house just to get your body moving and your heart pumping a little, there is good news. Studies have shown that even small amounts of light physical activities like these can yield positive health benefits-helping improve your mood, reduce risk factors for heart disease, and keep muscles and bones functional. However, if these activities comprise the full extent of your weekly exercise program, and you want to live even better and longer, you might be wise to step up your exercise intensity. A continuing study of 17,300 Harvard alumni suggests that increased longevity is correlated with the intensity of the exercise program. Researchers found a significant increase in life expectancy among the male subjects who regularly engaged in vigorous exercise, but not those whose activities were considered more moderate, or nonvigorous.

According to Jeff Zwiefel, an exercise physiologist and director of the National Exercise for Life Institute (NEFLI), "This research shows the importance of engaging in vigorous exercise that elevates the heart rate. We want to encourage everyone to at least begin exercising at a level that's comfortable for their age, fitness level, and ability. Once they start, they can gradually increase their intensity until they are exercising at a more vigorous level."

To inspire the 60% of Americans who are presently sedentary to get at least a little exercise, the Centers for Disease Control and the American College of Sports...