People who thrive under pressure do not necessarily seek out particular professions, researchers say. But whether they are on the trading floor or the campaign trail, they all appear to have had early experiences in difficult environments that taught them how to regulate their stress levels. They can sense when they are reaching their breaking point, and they know when to take a walk or turn off the ringer.

In some cases, these people subject themselves to stresses of their own making, driven by an unconscious urge to conquer pressures that dogged them as children or young adults, said Steven Kuchuck, a psychotherapist in New York who treats many patients who seek out demanding jobs and relationships.

"There's this strong desire to go back to similar sources of stress that they grew up with in an effort to master it," Mr. Kuchuck said. "Some people will say 'No, I don't like a lot of stress,' but they find themselves in one stressful job after another, so there must be something that's pulling them."

Mr. Kuchuck has also seen the opposite: people who crave a frenzied career because they feel their childhoods were not stimulating at all.

But regardless of what propels people to push themselves, what allows them to prosper, psychologists say, is a strong commitment to their career, a feeling of being in control, and a tendency to view stress as a challenge rather than as a burden.

People's attitudes toward their jobs and the degree to which they feel they make a difference by showing up each day have long been considered powerful indicators of how well they will do. Being just another cog in a machine with no say over what happens is almost guaranteed to cause burnout. But even in the most grueling work environment, people can cope if they feel they have some control.

Studies of professional musicians show that people in orchestras are often less satisfied and more stressed than those in small chamber groups because they lack autonomy, according to Dr. Robert M. Sapolsky, a professor of biology and neurology at Stanford and the author of "Why Zebras Don't Get Ulcers." Orchestra musicians are at the mercy of their maestro's every whim. For years, they had no power even to take regular bathroom breaks.