In the quest for good health, a hoe may be as important as a HealthRider.

Science has overlooked the holistic benefits of such reassuring daily acts as walking the dog or weeding the garden, says James Rippe, director of one of the world's leading research labs on health and fitness.The 48-year-old Rippe has devoted his career to figuring out the keys to fitness and he's come to believe in a link between emotional and physical well-being.

The mind-body connection is the underpinning of a new book, "Fit Over Forty," by Rippe, a Harvard-educated cardiologist and head of Tuft University's Center for Clinical and Lifestyle Research.

"I feel we have underestimated the importance of optimism and happiness as health-promoting factors," Rippe says.

He cites a National Institutes of Health study that found avid gardeners face a lower risk of heart disease. Rippe doubts that gardeners are gaining an aerobic workout from pruning.

"Gardeners by their very nature are optimists," he says. "I think it has to do with planting things, tending them and watching them grow."

Studies also show decreases in blood pressure and heart rates when people pet their animals, Rippe says. And pet owners are more likely to survive heart attacks than individuals who live alone.

That doesn't mean a vegetable patch and a poodle assure a longer, more vibrant life. Exercise and diet still play vital roles.

But Rippe says that we don't have to run marathons. Rippe served on the national panel convened by the Centers for Disease Control and Prevention and the American College of Sports Medicine, which concluded that adults should accumulate at least 30 minutes a day of moderate physical activity. (Boomers who have been sedentary should consult with a doctor before commencing a rigorous exercise regimen.)

Rippe says nooks and crannies of daily routines can accommodate exercise. Pointing to a nearby parking lot, he says the effort can be as simple as parking in the farthest spot and walking to the door at a determined pace.

Jumping up, Rippe demonstrates an effective walking rate. "I like to use Harry Truman's definition," he says. " `Walk like you have some place to be.' "

Once you've established a walking schedule, Rippe advises incorporating strength training with hand weights and stretching.

Neither do we have to resort to a macrobiotic diet for good health. Rippe prescribes a simple three-pronged approach to nutrition.

- Begin each day with a low-fat, healthy breakfast because research shows you'll eat less fat during the rest of the day.

- Take in five servings per day of fruit and vegetables. Less than 10 percent of Americans meet the five-alive guideline set by the National Cancer Institute, even though Rippe calls it the sole nutritional practice shown to decrease the risk of cancer. A banana and orange juice in the morning, an apple at lunch and salad and a vegetable at dinner meet the quota.

- Drink more water and fewer soft drinks. Start with three eight-ounce glasses each day. The average adult drinks 500 cans of soda a year, says Rippe, which translates to 25 pounds of refined sugar.

Rippe practices what he preaches. When his book tour escort suggests lunch, he requests a turkey sandwich with mustard, an apple and bottled water. After demonstrating the basic stretches from his book at the local Y, he remains to do his own workout, something he's managed to accomplish every day of his monthlong tour.

A philosophical bent runs both through Rippe's book and his reflections on health after 40. In his own life, the joyous birth of his first child nine weeks ago, daughter Hart, has given him more cause to contemplate.

If we divide life into seasons, baby boomers are in the late August or early fall of their lives, he says. "Fall" he quotes from poet John Berryman, "comes to us as a prize to rouse us toward our fate."

It's his patients who have taught him that the prize is the ability to live life to the fullest and with meaning. He recalls an 82-year-old patient who complained of occasional chest pain. When he learned that she climbed two flights of stairs to teach a Sunday school class, Rippe told her to give it up.

"What keeps me alive," she told Rippe, "is teaching Sunday school."

That was seven years ago, and the woman is still going strong, says Rippe. "I learned then that a little angina was nothing compared to the joy of teaching Sunday school."