Last winter, Roger Lewis had a toothache. It was just a little molar infection that cleared right up when his dentist did a root canal. But, deeper inside, Lewis's body was keeping a secret from him, the way rocks shift silently underground before the earth splits open.

"I'm as healthy as anyone in America," Lewis, a doctor, boasted to his dentist when he was treated for the abscessed tooth last January. But one night in April he woke up sweating so fiercely that the sheets were soaked. The infection had worked its way to his heart, leaving him with subacute bacterial endocarditis, an inflammation of the lining of his heart.He was hospitalized and given 24 million units of penicillin a day. By June he was feeling well enough to fly to Los Angeles to attend his son's wedding.

But his body was planning one more seismic upheaval. On a Sunday night in early July he noticed that he couldn't speak without slurring his words; then his left arm and leg went numb. At age 48, Lewis was having a stroke.

The irony was that Roger Lewis was, as he describes it, "the quintessential preventive medicine man." He had jogged 20,000 miles in the past 15 years, studied his cholesterol levels as if they were scriptures, followed a high-fiber, high-potassium diet. Two years ago he quit his family medicine practice to work full time developing seminars about stress and health.

There was, he admits now, a certain priggishness to his approach. He suspects that his patients were probably uncomfortable talking about their illnesses with him, for fear that he would chastise them for being so weak-willed that they couldn't stay well.

Lewis is feeling more humble these days. Two hours a day of physical therapy, bending your limbs till they ache, makes you remember your limitations.

"Now I'm aware that nobody assigned me to clean up any temple," he says. "Now I can see I can't point accusing fingers at anyone."

But if he's less likely to feel that good living necessarily leads to good health, he believes more strongly now that good thoughts can help a body heal.

In the hospital, on the night of his stroke, doctors told his wife he might be paralyzed on his left side for the rest of his life. Lewis, a student of the new field of "mind-body medicine," decided right from the start that he would use his mind to bring life back to his paralyzed limbs.

But it wouldn't be a matter of just willing himself whole again.

As he lay in his hospital bed in Provo he thought for hours about his relationships with other people. What he was trying to do, he explains now, was let go of the feeling that he was separate from other people or from God. You can't heal, he says, until you let go of self-pity and isolation.

"Most people assume what I did all day was picture myself walking again," says Lewis. "But the greater healing force came from my willingness to see that everybody I meet is a potential friend."

That willingness was challenged by nurses who insisted on treating him like an infant. "It was overwhelmingly easier to think, `Look . . . , get out of here!' But I knew that if I wanted to be healed I needed to see them as friends. I had to see their efforts as efforts to help me.

"So when they changed my diaper I would say, `We make a good team.' I think that was as important as anything in establishing a healing environment." Lewis pauses. "The healing environment was my own mind."

By the end of July, less than four weeks after his stroke, Lewis was beginning to walk again. At night he would lie in his hospital bed and fantasize about fulfilling his commitment to teach wellness classes at BYU's Education Week. He fantasized about having the class sing Beethoven's "Ode to Joy," although he could hardly think of the words without crying.

Even now, months after his stroke, even though he is at home and teaching seminars again and able to walk 2 miles through the snow, there will be things that will reduce him to tears.

He starts to quote his favorite line from "Gunga Din," but the left side of his face begins to sag with the emotion of it all.

When he regains his composure, he explains: "Strokes on the right side of the brain often remove those facilities we have of masking our emotions.

"But that allows me to enter into relationships that are honest. . . . As my more sensitive friends have pointed out, there's more congruity now between what I've preached and what I am."