Although there is no precise prescription for thwarting any one disease, the overall message is clear: Get up, and get moving.

I'M TOO BUSY

Experts say the "life is too hectic" excuse is by far the most common one. Trying to cram in an exercise regimen with work, personal relationships, friends, family, and errands may seem futile. But people who exercise are busy, too. They just make working out a priority. "Anything that is important to you, you'll find the time for," says Chris Imbo, managing director of health lifestyle company Welldome and a personal trainer. His client Jonathan Tisch, cochairman of the board of Loews Corp., works out five to six mornings a week, either with Imbo--usually lifting weights in the gym--or on his own, running in Central Park or using a treadmill or elliptical trainer indoors. "It's embedded in my way of thinking," says Tisch, 52. "It's like brushing my teeth."

Working out also may not take as much time as you think. "You can spend a relatively minimal amount of time--30 minutes on most days--and it will give you such a big return," says Cedric Bryant, chief science officer with the American Council on Exercise. You can also accumulate exercise throughout the day, say, by taking the dog for a brisk 15-minute walk in the morning and then again after dinner.

Experts also say the best way to fit in exercise, as Tisch does, is to work out first thing in the morning. You're a lot less likely to have competing demands on your time at 6 a.m. than in the evening. Many gyms open at the crack of dawn, and some are even open around the clock. If you are not a morning person, schedule sessions when you are less likely to blow them off and try writing them on your calendar or BlackBerry like a meeting. There will be trade-offs. "Everyone has different demands on their time and money," says Chideya, who is chronicling her efforts to get in shape on the National Public Radio show News & Notes with Ed Gordon. "That's just the way it is."

I'M TOO OLD

Nice try. Almost no one is too old or too frail to exercise. Because of the natural decline in muscle mass--about 10 percent per decade starting around age 50--and dwindling aerobic capacity, the need to stay active may be more apparent in old age than at any other life stage, says Kerry Stewart, director of clinical and research exercise physiology at Johns Hopkins University School of Medicine. "It's really important for young people to stay active to maintain health, but for older people," says Stewart, "it may be even more important to stay active to have some way of fighting off the natural processes of aging and resist chronic diseases." The American College of Sports Medicine recommends that older adults follow the same 30-minutes-a-day routine, including aerobic activity and strength training. For the homebound, strength training can be done using a chair. For example, an elderly person could hold on to it for balance while slowly lifting and lowering the leg to build up hip and thigh muscles. A study presented at the ACSM's annual meeting last month found that gardening activities like weeding, mulching, and transplanting seedlings were enough to qualify as low- or medium-intensity exercise and easily fulfill the 30-minutes-a-day plan. And research published in the spring showed that older adults who participated in an hourlong tai chi class three times a week for 12 weeks improved their balance, strength, endurance, and flexibility.