(FORTUNE Small Business) – James Herrera is an artist, and his medium is the human body. He draws out the superhuman in ordinary people, taking flabby wimps and sculpting them into high-performance machines. Technically Herrera, 36, is a personal trainer, but that's like saying that Tiger Woods plays some golf. Over the years Herrera has helped athletes in sports ranging from professional motocross to Olympic-caliber track and cycling.

Herrera is also the head of coaches at Carmichael Training Systems (CTS) in Colorado Springs, a company that trains pro athletes in individual sports. Lance Armstrong is the company's most famous star, coached mainly by its eponymous founder, Chris Carmichael, who started working with Armstrong back in 1990 when he was still a junior cyclist. Carmichael has a few fitness books out, and Armstrong is quoted on the covers, saying "Chris Carmichael has been my coach, my trainer, and my friend for more than a decade. I would not be a Tour de France champion without him."

CTS also takes on out-of-shape amateurs such as me. It has three training facilities (two in Colorado and one in Philadelphia), but the twist is that most of the amateurs are trained remotely, by phone and e-mail. About 95% of its customers never see the facilities.

To see how such virtual training works, I signed up for three months with Herrera as my coach. Most clients come in with specific goals in mind, from running a marathon to losing weight to, in Herrera's words, "riding their local Tour de France." When Herrera asked about a goal I said half-jokingly, "Six-pack abs, like those guys in fitness mags," and then, more seriously, "A half-marathon, averaging seven-minute miles." CTS offers three main packages that range in price from $49 to $499 a month (plus an $89 initiation fee), depending on the coach you want and the attention you need. I opted for the most advanced package, which gave me round-the-clock access to a coach who trains Olympic and professional athletes, plus a dietary analysis, a personal nutritionist, and a health evaluation.

At the start of Project Me, I weighed 180 pounds, and my 6-foot frame, once athletic from high school hockey and cross-country, had gotten a little, um, doughy. When I was 17, I consistently ran 5-K races in 17 minutes, bench-pressed 225 pounds, and easily blew through 100 pushups. I had worked out frequently until I was 25 but had stopped after that. I'm 30 now and had not seen the inside of a gym in two years (unless you count on television). Stairs winded me, insomnia haunted me, and I thought Viagra might not be that far away.

Confessing all this to Herrera was like being on a shrink's couch. (He has a master's in exercise physiology and another in psychology.) "Is there anything else I should know?" he said several times. I asked whether beer counted as a "recovery drink" after exercise. No response.

While Herrera crafted a fitness strategy, I talked to a genial nutritionist named Ashley about my diet. A lack of water was the first thing she noticed. I hardly drank any. "Always keep a 32-ounce water bottle with you," she said. "Drink four of those a day." And fruit. "You have to eat more of the real stuff, bananas, oranges. Stay away from anything processed." Then there was the coffee, which really hurt. She wanted me to drop from my customary ten cups a day to three. No sugar. No cream. Whole-grain pasta and rice had to be substituted for the white kinds, which were empty calories. And no more ice cream!

A day later Herrera e-mailed me his master plan—a seven-day fitness schedule that included six days of running and weight training and one day of rest. Sounds like a lot? It did to me. "One day of rest?" I said incredulously.

"Welcome to your new life," he said.

Chris Carmichael, 42, raced for the 1984 Olympic cycling team and launched CTS in 1999 after Lance Armstrong's first Tour de France victory. The timing was serendipitous. "We really grew fast," Carmichael told me from a private jet one afternoon, when he and Armstrong were traveling back to the CTS Colorado facility after a training session. The center has more than doubled its client roster every year, from a handful of athletes in 1999 to more than 3,000 worldwide in 2004. All 95 of its coaches—there are 20 on-site and 75 around the U.S.—have secondary degrees, and before going live, they must spend six months in a residency program to learn the CTS methodology, boning up on everything from body mechanics to heart-rate monitoring to proper coaching language. In 2005, CTS will launch an exclusive diet-coaching program for active people as well as a co-branded line of fitness foods. Two rounds of venture capital funding, totaling $5 million, have helped fund its growth. CTS has a few competitors, including Multisport.com and TrainingPeaks.com.

For three months I ate, walked, slept, and dreamed CTS. Every week Herrera posted my fitness schedule online so I could log in and see any changes. Mostly I worked out in the mornings. The alarm rang at 5 a.m., when it was still dark outside and the bar next door was just closing. With my iPod cranking out Eminem and 50 Cent, I was running three to five miles a day, averaging nine-minute miles, and hitting the weight room for a half-hour after that, working both my upper and lower body. I loved the Nautilus curl machine, which allowed me to do three sets of 40 pounds while watching celebrity biopics on VH1. I hated the bench press, mainly because I could do only three sets with 125 pounds while everyone around me was lifting twice that, including a very large Grace Jones look-alike. "Big man," she'd always joke with me.

The first month and a half wasn't pretty. Herrera changed my workout three times, exchanging a day of running three miles for biking ten miles, for instance. When the days were over, my body ached. I skipped dinner parties because I didn't want to sit for very long. When I went to bed, I couldn't sleep. I felt as though I was still running or biking or bench-pressing. And my back felt permanently bent over, as if I was perpetually hunting under the couch for the remote control. My body didn't appear to be changing, except that it hurt more than when I wasn't doing anything.

"Is this supposed to be fun?" I asked Herrera one day after a five-mile run. I had started to use an elastic heart-monitor band around my chest, wired to a wrist display that showed my pulse. My heart was going wild on runs, averaging 185 beats a minute. Like a certain brand of New Age guru, Herrera exudes an endless sunny optimism. "Progress doesn't happen overnight," he told me more than once. "What we want to do is establish consistency. It's a chipping-away process." Still, he mixed things up when he thought it would help keep me fresh and motivated. Once he surprised me with a day off. Another time he substituted full-court basketball for running.

According to Herrera, most of the people who come to CTS—aside from the professional athletes—are a lot like me. The average age is between 35 and 45, and most are ten to 20 pounds overweight and are looking to get back into shape or, as Herrera puts it, "beat their buddy up the hill." More than 65% of CTS's clients have been onboard for three years. Very few quit, which makes sense, given the alacrity with which Herrera started calling me when I lost my enthusiasm for the project.

Typically, I talked to Herrera three or four days a week for about 20 minutes each call. Sometimes the calls were scheduled. Other times I would call him on his cell or at his office. If I needed it, we would talk more—which was the coolest part of the program. He was extremely accessible, by cellphone and BlackBerry. We talked after 9 p.m. some nights, and even on weekends. All the attention made me feel like Herrera's only athlete. Which wasn't true. In fact, like most of the coaches, he juggles 20 to 30 clients at once.

And then I turned the corner. It happened just after the beginning of month three. The runs were now longer (up to ten miles), but I was going faster (an eight-minute pace). And I didn't always need to bring the iPod. In the gym, I was bench-pressing 175 pounds. Even Grace Jones noticed. "You're a fighting man," she said one morning, as I powered through a third set. Other days, I was cycling 20 or 30 miles. My heart rate was steadying at 155. I didn't ache. And I had lost nearly ten pounds.

Still, I had a feeling that the 5 a.m. alarm and the 90-minute workouts couldn't last. When I wrapped up the third and final month, Herrera called for the last time. It was a Monday, and I had a lot of work to do that week. Without Herrera to coach me, I knew I wouldn't make it to the gym. Working out this way is a lot like a serious relationship—it takes time and energy. And you can have only so many relationships in your life at once. Simply said, there were other things I had to do now: parties to attend, ice cream to eat, football to watch, and long, luxurious mornings of sleeping in until 7 a.m. And when Herrera hung up that day, though I would miss his cheery phone calls, I was ready to say goodbye.