Efforts to lose weight, to stop smoking, and to stop or reduce drinking have proved more successful if combined with an exercise program. A Perdue study showed that middle-aged men who completed a four month exercise program showed increased emotional stability, self-sufficiency, and imagination. Another study showed that runners have more self-confidence and a better self-image than nonrunners. And Thaddeus Kostrubala, M.D., a psychiatrist who prescribes running to his patients, writes, ''I have talked to many runners—runners who run long, medium, and short distances—and I have come to the conclusion that running, done in a particular way [long and slow, using a target pulse—Ed.] is a form of natural psychotherapy. It stimulates the unconscious and is a powerful catalyst to the individual psyche.'

A Positive Addiction
It is helpful to remember, in the early stages of an exercise program, that at a certain level of fitness, exercisers begin to "get hooked"—exercising becomes something you look forward to, something you feel deprived of if you are forced to do without. Runners, walkers, swimmers, and other athletes describe a certain feeling that comes over you in the midst of an exercise session. I've heard it described as a "second wind, " a "letting go," a "being at one with the world."

Like all emotional states, it's hard to pin down in words. One fifty-five-year old runner, asked to describe the feeling, said that it was like trying to describe love to someone who has never been in love. Only walkers, runners, swimmers—and lovers—know.

One researcher who set out to study exercise addiction ran into problems which illustrate just what an important part of life exercise can become. He wanted to look at physiological changes in athletes who stop exercising. After interviewing a great many people who exercised regularly, he was forced to give up his project. He could not find enough people who exercised regularly who were willing to stop.

"Notwithstanding the fact that they were being offered higher pay than usual," he wrote, "many prospective subjects (especially those who exercised daily) asserted that they would not stop exercising for any amount of money."