Leslie Fredrickson can't abide formal exercise programs.

"They're a bore," says the 72-year-old retired Agriculture Department program manager. "I used to do a half-hour exercise routine of push-ups and sit-ups and the like at home, but it got to be so darn boring that I quit. And it's too much of a pain in the neck to drive to some gym."

Instead, Fredrickson keeps himself in top shape by spending several hours a day gardening at his Germantown, Md., home. "Planting, weeding, splitting wood and all that is excellent fitness work," says Fredrickson who's been gardening since he was "a wee tad" in Oregon. "I just dug a two-foot hole and planted a weeping cherry, and that's the kind of thing that keeps me fit."

In addition to the physical benefits, he says, "I get beautiful flowers, lots of vegetables and my place looks nice. I know gardening's good for me, I enjoy doing it and it's never boring. So I win on all counts."

Fredrickson is among a growing number of Americans -- many of them over 50 -- who have discovered the physical, mental and spiritual benefits of gardening. At a time when public health officials are touting the advantages of regular moderate exercise, gardening is gaining recognition as a healthy lifestyle activity that can provide significant benefits to people of all ages. The U.S. Surgeon General's 1996 Report on Physical Activity and Health concluded that accumulating 30 minutes a day of moderate activity, such as gardening, can reduce risk for numerous chronic conditions -- including heart disease, type 2 diabetes, hypertension and colon cancer -- and aid in weight maintenance and overall physical functioning.