(FORTUNE Magazine) – Six months ago, 33 men and women ages 49 to 72 checked in to the Life Enhancement Center at the Canyon Ranch complex in Tucson for the kickoff of a new program called Optimal Aging. I was a member of the group--the skeptical one. I mean, now that boomers are in their 50s and Viagra reigns as the recreational drug of choice, there's no shortage of programs selling us on graceful aging. The Canyon Ranch program looked suspiciously like yet another attempt to jump on the longevity bandwagon.

I was wrong. It turned out to be a cool gig. The food was great. We had serious one-on-ones with M.D.s, psychologists, and exercise physiologists who know their stuff. Outside experts gave us the skinny on everything from nutrition and stress to herbal medicine and cardiovascular fitness. We got insights into the latest thinking on the prevention and treatment of Alzheimer's, hypertension, arthritis, and the other aging phenomena we worry about. We meditated. We worked out. I lost four pounds.

Okay. Four pounds isn't much to brag about, but the Optimal Aging program isn't about short-term transformation. It's about changing how you live. "Back when Canyon Ranch was essentially a fat farm," one of the old-timers told me, "we'd put the guests on an 800-calorie-a-day diet and work their butts off. They'd lose ten to 12 pounds in a week. But when they headed down the driveway, their first stop would be McDonald's or Burger King."

Which brings us to the real questions: Did my weight stay off? Did the lessons I learned sink in?

The answers are yes, and yes again. In addition to the four pounds I left in Tucson, I dropped another ten after I got home--and they've stayed off despite a two-week, lobster-filled vacation on Cape Cod and the business lunches that go with my everyday territory. But that's only part of the story. The headaches that used to plague me have just about disappeared. My blood pressure is down. Same goes for my cholesterol. I wake before the alarm goes off in the morning, and I've got energy to spare at the end of the day. (Full disclosure: All of the above are great, but the thing I really love is that for the first time in 15 years, I've got a waist.)

So what's the secret? The answers won't shock you if you've been at all conscious during the past decade. I now have breakfast every morning. I rarely eat meat. I limit myself to one cup of coffee a day, drink lots of water, and have discovered that I can do without beer at lunch and Scotch at night. I take vitamins and supplements. I don't exactly meditate, but I do carve out a couple of minutes twice a day to stare into space and focus on breathing. I make it to the gym two or three times each week, and I manage to get a little exercise on the off days.

This, of course, is stuff we all know we're supposed to do. The difference is that the folks in Tucson got me from "supposed to" to actually "doing." How'd they do it? A combination of things. The Canyon Ranch people are skilled at conveying what they know. And, for lack of a better term, there was peer pressure. Lots of it. It helped that members of my group constantly reinforced the messages we heard. So did the fact that I was ready. I had done too much yo-yo dieting and seen too many friends go down with heart attacks. This time, I wasn't just writing all the do's and don'ts in my three-ring binder; I was ready to put what I was hearing into practice.

The 33 of us in the program--ten couples, 13 individuals--came from 15 states. Occupations ran the gamut: lawyers, money managers, business consultants, a judge, a Napa Valley winery owner, a social worker, and an associate commissioner of education from Connecticut. I was the only writer and, at 64, in the middle of the age range. We were a serious bunch. We had demonstrated that a month earlier by filling out a 20-page "Confidential LifeStyle Questionnaire," which gave our counselors-to-be at Canyon Ranch an intimate view of virtually every detail of our daily lives. To plug in the remaining blanks, the medical staff drew seven vials of blood from each of us the morning of our first day in Tucson.

We were shown to adobe rooms and casitas that were large, luxurious, and stocked with all the amenities you'd expect from a spa with a weekly tab of around $5,000. Not that we spent much time in our rooms. Our days were packed with activity. But it wasn't boot camp either. If you needed a break, it was okay to sit in the shade and contemplate the cacti and bougainvillea.

Each day began at 7 A.M. with two choices: a brisk walk through the desert or a session of tai chi or chi gong. Next came a short period of meditation, then breakfast featuring an egg-white omelet bar. Nine to noon was serious stuff: (1) lectures on exercise, stress, weight control, vitamins, antioxidants, memory, heart disease, the aging frame, chronic fatigue, sexuality, and insomnia; (2) classes in strength basics, weightlifting, agility, balance, yoga, water aerobics, and dance; and (3) individual consultations with Canyon Ranch doctors, nutritionists, fitness instructors, and psychologists.

Lunch, which ran from noon to one, was often accompanied by a minilecture on an aspect of nutrition or a demonstration of how to prepare a great-tasting, low-calorie meal. The afternoon was a rerun of the morning--lectures, classes, workouts, and one-on-ones. Dinner featured a pasta bar, lots of salad and veggies, and your choice of meat, fish, or poultry. The evening activities, which ran from 7:15 to 8:30, varied--a discussion, a demonstration, even a campfire with roasted marshmallows.

Dr. Evan Kligman, the gerontologist who designed and runs the Canyon Ranch program, set the tone in his opening lecture. We know lots about aging, he said. We know, for instance, that easily measured things like strength and the body's ability to use oxygen decline with age. Still, said Kligman, who teaches at the University of Arizona College of Medicine, there is no scientific way to determine why some people in their 80s and 90s remain active, alert, and happy while others wind up hobbling around with walkers or living out their lives in nursing homes.

Full stop. Although all of the above is true, the men and women who demonstrate what Kligman called "enhanced adult health status" have a lot in common. They sleep seven to eight hours a day, eat breakfast, don't eat between meals, keep their weight within 10% of ideal levels, exercise regularly, don't smoke, and consume little or no alcohol. That's it? Yup. Kligman said that the blood work his team was doing would provide insights into the vitamins and supplements we need. Then they'd do a personalized assessment of our day-to-day lives. Of course, there are differing opinions about whether all drinking is bad, or how useful vitamins and supplements really are, but the Canyon Ranch goal was to get us to adopt new behaviors, then help us figure out how to maintain them when we left Tucson.

By the end of day two, it was clear how they intended to do it. Regardless of which activity we were engaged in, every presenter was working from the same playbook--eat right, exercise daily, reduce stress. Okay. Intellectually, we got it. But how do you make it happen?

In my case, the exercise part was easiest. I spent my formative years in a gym, and working out has always been part of my life. So Karen Nelson--the exercise physiologist assigned to my case--and I talk the same language. When she said my abdominal crunches would be more effective if I tightened my stomach muscles on the way down, I immediately felt the difference. Same thing when she watched me go through my weight routine. Add a few more pounds to each exercise, she said. If you can bench press 120 pounds ten to 15 times without straining, keep adding weight until you reach the point where you can barely make it. Then rest for two minutes, and do another ten to 15 repetitions. Then rest again and repeat the procedure a third time.

There was more. Bench pressing is great for your chest, Nelson said, but you need to give equal time to working the muscles in your back. You don't want to throw your body out of balance. As for the treadmill, the 20 minutes at a four-mile-an-hour pace I do makes sense, given the fact that I've had surgery on both knees, but 30 minutes would be better, and it would be better yet if the treadmill were set on an incline. "To get a real aerobic benefit," said Nelson, "you need to break a sweat, and you want to push yourself to the point where you can't carry on a normal conversation while you're working out."

Thing is, while I get a kick out of crunching and grunting in a gym, the only place I really like to sweat is on a squash court, which is tricky because I've had two lumbar disks and a hernia patched up in the past ten years. Holly McCarter, a psychologist whose job was to guide me through an assortment of midlife issues, listened to my tale for about ten minutes, then came up with the answer. "If I hear what you're saying, you're not interested in winning matches. You want to be on a squash court because you get pleasure out of running around and hitting the ball. So what's the problem? Just change the rules."

So here's my new routine. I now play squash once or twice a week, but instead of trying to win points by blasting the ball past my opponent or making it die in the front of the court, I give myself a mental point each time I keep a rally going and another point each time I don't kill myself by attempting to return a particularly difficult shot. I'm not winning tournaments, but I'm having a blast being back in the game. In addition to squash, two or three times a week I get to the gym, where I go through a 50-minute routine that employs the tweaking Nelson prescribed. Having learned that any exercise is better than none, I also throw in other tricks I learned in Tucson: Make stretching as routine as brushing your teeth, get off the subway one or two stops early and walk, use the stairs instead of an elevator.

Changing my eating habits was harder. The food at Canyon Ranch bordered on gourmet, and the calorie, fat, and fiber counts that went along with each item made it clear the food fit into the good-for-you category. And yet I was never hungry. How come? Maybe breakfast had something to do with it. Maybe the fact that most things we ate were high in fiber. Maybe my eyes had always been bigger than my stomach: the steak, chops, and veggie burgers were only three ounces, but they were filling. And although ice cream and cake were usually on the menu, the yogurt and fresh fruit that came as options were delicious.

It took a few months to incorporate Canyon Ranch nutrition into my home routine, but I did it. In place of a bagel and cream cheese at breakfast, I now usually have a hard-boiled egg, a slice of whole-wheat toast, and a banana or a cup of berries. By snacking on fruit, I'm no longer famished at lunch and dinner. Cutting back on red meat was hard, but I like chicken and my wife does a fabulous job on salmon, tuna, and swordfish. Alcohol was easy. I just stopped. Coffee was harder. I had been doing six to eight cups a day; I've weaned myself down to one at breakfast and I fill in the gaps with green tea (which you can get used to) and lots of water. Carrying a bottle of Poland Spring into a meeting makes me feel totally yuppie.

I've always been into vitamins and supplements. Before Canyon Ranch, my daily intake included a heavy-duty multivitamin, extra vitamin C and E, a few Tums for calcium, and a bunch of supplements. After my blood work was analyzed, the Canyon Ranch doctors said I might want to add two others to the mix: coenzyme Q-10, an antioxidant that helps fuel cellular activity, and folic acid, a member of the B vitamin family, which helps make red blood cells and is thought to protect against heart disease. Do all these things really work? Beats me. I'll tell you in 20 years.

Getting a handle on stress involves a lot more than popping a few pills, and I still have a long way to go. I live in New York City, and my business revolves around deadlines. Two strikes right there. The tai chi I did at Canyon Ranch was a great stress buster, and the videotape I brought home is easy enough to follow, but a flesh-and-blood leader and a group setting are what make tai chi work. Yoga is good, but it takes time I don't have.

I do have time for a couple of two- or three-minute stare-at-the-wall breaks every day, and focusing on breathing does clear my mind. A suggestion from Phil Eichling, the medical director of Canyon Ranch, also works for me: Change your expectations of the people around you. If I recognize that people are not going to return phone calls when they say they will and that my computer is not going to work flawlessly, it's easier when the calls don't come and my Mac crashes.

Not that any of this stuff is easy. I got a letter recently from John Bruens, CFO of a cable network in West Virginia, who said he and his wife, Kay, talk about their Optimal Aging experiences all the time. But then he wrote: "We had a lot of fun and met some great people, but have found it difficult to stay with the program. Old habits are hard to break." I haven't heard from half of the others I e-mailed, which suggests that the Bruenses were not the only ones who struck out.

But there were lots of singles and doubles. Dave Redo, president and CEO of Fremont Investment Advisors in San Francisco, now lifts weights two or three days a week, walks 30 minutes five or six days, takes vitamins, and has overhauled his eating: "Fish or chicken most days. A lot more salads and fruits. I hardly ever eat beef. Overall, I feel a lot better, and I have a lot more energy."

Michol Oconnor, a judge from Dallas, now exercises seven to ten hours a week. "I'm in training for retirement," she says. "My term is up at the end of next year, and I am not going to run for office again. I want to be in good health and in great shape to take on the challenges of this new part of my life."

Some of the things they wanted us to do at Canyon Ranch were weird. I, for one, did not set my alarm for 3 A.M. the first night to spit in a bottle so that the medical staff could measure my melatonin level. But I like the mantra they left us with: "The goal of a personal longevity program is to add life to your years, not necessarily years to your life." I like the lifestyle changes I'm still into six months later. My stomach isn't rippled, and I'll never do a four-minute mile, but I like the way I feel and the energy I have. Have I fallen off the wagon? Of course. Hey, weddings, deadlines, and the flu will make a mess out of anyone's best intentions. But there's a simple answer: every time I stumble, I just get back on and pick up where I left off.