BEN LERNER is the rare celeb who looks as waxy and new in person as he does in his author photos. He has a delicate, almost pointy face, blazing red hair, and a well-toned torso that shows through his skintight shirts.

I first met him in early June, in Winnipeg, Canada, where he was consulting with several chiropractors and speaking at the midweek evening service at Springs Church, a 10,000-member congregation that's the largest in Canada. He had brought his family along: Sheri; their two-year-old daughter, Nicole; and ten-year-old Skylar, Ben's son from a previous marriage.

I arrived at the Lerners' Winnipeg hotel about an hour before the Springs Church engagement and found them sitting quietly in the lobby. Before I could even shake Lerner's hand, a tall, square-jawed man in a suit and sunglasses—he could have doubled as a Secret Service agent, although I later discovered he was the Springs Church accountant—strode into the hotel.

"Are you ready?" he asked Lerner curtly, introducing himself as Mike, the evening's driver. Mike hurried us into a sleek, spacious SUV, then slipped behind the wheel and began droning into the tiny headset clipped to his ear. "Yes, sir," he told his contact at the church. "We'll be there in ten minutes."

As we navigated the streets of downtown Winnipeg, Lerner simultaneously played with his daughter, riffled through a pile of papers, and looked up occasionally to answer my questions.

"My husband is a master at handling time," said Sheri, who accompanies Lerner on a third of his trips. "It's his greatest strength. He can switch from doctor to dad to husband to author. He wrote his book in 30-minute chunks, once a day. Some people would take 15 minutes just to warm up."

I found Lerner's most impressive trait his ability to stay on message—he smoothly avoided almost all my attempts to get beyond his stage persona. When we talked about his past, I heard the same scripted story I'd read in his books and heard in his speeches. What Lerner doesn't write or preach about—but what he told me later, back at his hotel—is that his conversion to Christianity came fairly recently.

Benjamin Solomon Lerner was born in Queens in 1966. As he describes it, his childhood sounds like something right out of a Woody Allen movie.

"We were a typical New York Jewish family," he said. "Love was more implied than shown, and my father had a kind of pessimistic attitude. The culture I came from was high-stress and panicked—people always worrying about success and making money—and it was killing my family members quick."

The men in Lerner's extended family—including his father, Marvin, who died of a heart attack at 52—were overweight and suffered from high blood pressure and high cholesterol. Ben's mother, Dorothy, now 62, predicted that Ben, too, would become obese by the time he hit his late twenties. "I thought that was funny," Lerner said with a wry smile, "because my friend Billy's mom was always telling him that at 30 he would be an attorney."

When Ben was four, the family moved to Ohio, and he grew up in Cleveland and Columbus, where he attended synagogue and had a bar mitzvah. In high school, Lerner discovered wrestling. But during his freshman year at the State University of New York at Albany, he realized he would never make the varsity team with a body plagued by constant injury and illness. Seeking relief from shoulder and back pain, Lerner first saw a chiropractor in 1987. That visit, he likes to say, was "a revelation"; his health improved immediately, and he began to turn his life around.

Benjamin Solomon Lerner was born in Queens in 1966. As he describes it, his childhood sounds like something right out of a Woody Allen movie.

"We were a typical New York Jewish family," he said. "Love was more implied than shown, and my father had a kind of pessimistic attitude. The culture I came from was high-stress and panicked—people always worrying about success and making money—and it was killing my family members quick."

The men in Lerner's extended family—including his father, Marvin, who died of a heart attack at 52—were overweight and suffered from high blood pressure and high cholesterol. Ben's mother, Dorothy, now 62, predicted that Ben, too, would become obese by the time he hit his late twenties. "I thought that was funny," Lerner said with a wry smile, "because my friend Billy's mom was always telling him that at 30 he would be an attorney."

When Ben was four, the family moved to Ohio, and he grew up in Cleveland and Columbus, where he attended synagogue and had a bar mitzvah. In high school, Lerner discovered wrestling. But during his freshman year at the State University of New York at Albany, he realized he would never make the varsity team with a body plagued by constant injury and illness. Seeking relief from shoulder and back pain, Lerner first saw a chiropractor in 1987. That visit, he likes to say, was "a revelation"; his health improved immediately, and he began to turn his life around.

Lerner transferred to Life University, a chiropractic college in Marietta, Georgia, during his sophomore year. By the time he was 30, in 1996, he had graduated with degrees in nutrition and chiropractic and settled in central Florida. (He married his first wife in 1993, divorcing a year later.) He was serving as the official chiropractor for the U.S. Olympic wrestling team and running one of the largest chiropractic clinics in the world—the Lerner Family Chiropractic Center, in Kissimmee. His health was good. He was fit. Yet he didn't feel settled.

"Deep down," he said, "I felt that something was missing." Until one day, in 1998, when the family of one of his patients invited him to the nondenominational South Side Christian Church. "There was just something about this family," he recalled. "So I decided to accept the invitation."

Given his strict Jewish upbringing, Lerner saw flirting with Christianity as "stabbing my family in the back." In church, however, he was overcome with a deep sense of peace. "It was a really great group," Lerner said, "and despite their circumstances, whether they had faced the death of family members or financial crises, they seemed happy."

In 1999, Lerner was baptized at South Side Christian. Two years later, he married Sheri Schatzenbach, a Christian chiropractor he'd met at a professional seminar in Atlanta. And when he decided to write the fitness book he'd been thinking about for several years, he infused it with a strong dose of religion.

"One of the keys to my success is that I stay relevant," Lerner said. "Right now, all the popular diets and fitness programs are failing. We have record obesity numbers. Most diseases are at their all-time high."

Sounds like what any fitness maven would say. But Lerner is always careful not to let the physical overwhelm the spiritual, emphasizing that it's possible to put too much focus on the body.

"It's like what my pastor says about people he sees running instead of worshiping on Sunday mornings," he said. "You may look good now, but how great will you look when you're on fire?"