CHICAGO -- At the outset it should be noted that God did not give Steve Fossett the body of a great adventurer. Five feet 10 inches tall and 190 pounds, he's barrel-chested and slightly paunchy -- chunky, to use a polite term. His brown hair is thin and his hazel eyes are myopic. Nobody will ever mistake him for Indiana Jones. Nor will they confuse him with Sir Edmund Hillary, although Fossett, 43, has climbed the highest mountains on five continents and this month will try to scale Mount Everest.

What Fossett has is grit, not grace; guts, not glory; patience, not panache. Unable to make either his high school cross-country or swim teams as a teen-ager in Garden Grove, Calif., he somehow found a way to run the Boston Marathon and swim the English Channel as an adult.

The channel crossing offers a certain insight into Fossett's personality: It required four tries over five years before he successfully traversed the 21 miles from France to England, and when he finally succeeded in September 1985, it was only after swimming more than 22 hours, the last five against a hostile tide. At the end Fossett was nearly unconscious and dangerously close to hypothermia in 58-degree water. His body was bruised and bleeding from being beaten against the rocky English coast. The sodium content of his blood was high because of all the sea water he had swallowed. And he couldn't talk because gasping for breath had left him hoarse.

"For sheer guts," the British Channel Swimming Association awarded Fossett its annual endurance trophy.

Fossett doesn't volunteer this information; it must be coaxed out of him. When he flew to Utah a few months ago to talk to Karen Fellerhoff about joining her expedition to climb Mount Everest, it took Fellerhoff two days to get Fossett to discuss his sporting achievements, which include, among others, riding in a 760-mile bicycle race and completing a winter triathlon -- 13 miles of cross-country skiing, 10 miles of hiking uphill in snowshoes and 10 miles of speed skating. He never did get around to telling her about his exploits in the world of finance, which turned him into a millionaire options trader in Chicago.

"Here's a guy who at 43 has had more adventures than I could ever hope to," said Fellerhoff, 27, who directs Snowbird Adventure Travel in Snowbird, Utah. "He's very understated."

Fellerhoff, who obtained one of only about a dozen permits issued each year to climb Everest, likes that. She and three other female members of the climbing team hope to become the first American women to reach Everest's summit. But they realize that to do so will require a collective effort. Blending personalities is crucial to climbing the world's highest mountain. Weather thwarts about half the attempts anyway; there's no need to lengthen the odds with infighting among the climbers.

Fellerhoff believes Fossett will blend neatly into her crew of 10 climbers. Having scaled more than 200 summits around the world, he is among the most experienced members of the team. But you would never know it to see him or hear him.

"I keep a relatively low profile," Fossett said. "I have never sought out publicity for sports. In a way, I live in two different worlds.

"Business is much easier for me. Sports is often very humiliating, because there are so many better athletes in these events. I would like to be the best in everything, but that's not possible. I risk humiliation because I have a genuine interest in participating."

Fossett has difficulty explaining what motivates him to flirt with athletic humiliation. "It's internal," he said. "It doesn't lend itself to explanation."

Given the level of his professional accomplishments, it is almost impossible to understand. From the ground up, Fossett built a corporation that employs 130 people to buy and sell stock options and process transactions from eight exchanges.

After getting an undergraduate degree at Stanford University and a master's in business administration at Washington University in St. Louis, he worked as a commodities broker. Over the next several years his list of clients grew to include the billionaire Hunt brothers of Texas. But Fossett never liked having to persuade other people to let him invest their money. So he took a block of his own capital and started trading options. Now 60 of his traders use his money to buy and sell on the floors of exchanges around the country.

Again, he doesn't blow his own horn terribly loudly, but the trappings of his success speak for themselves. There are the offices of Fossett Corp., which take up a chunk of the 24th floor of the Chicago Board Options Exchange Building. The president's digs occupy a corner with a panoramic view of the city. There are Fossett's homes -- a 3,400-square-foot condominium in Water Tower Place and a six-bedroom, 7,000-square-foot "weekend getaway" in the Beaver Creek resort near Vail, Colo., where Fossett shares a street with former president Gerald Ford and tire tycoon Leonard Firestone. Finally, there are Fossett's cars. In the city he drives a Bentley, in the country a Ferrari.

With all this, why would he risk humiliation, not to mention his life, on the slopes of Everest, a mountain that has claimed one victim for every two who made it to the summit?

That's a question Fossett's wife of 19 years may have asked herself a lot lately. Peggy Fossett refused to talk about her husband's latest adventure because she didn't have anything good to say.

"My wife," Fossett said, "really wishes I wouldn't do these things."

Fat chance. Fossett's fascination with adventure stretches to his childhood. He loved to read about polar explorers and mountain climbers of the 19th and 20th centuries. While most kids his age were enthralled with the fictional escapades of James Bond, Sherlock Holmes and Tom Swift, Fossett immersed himself in the real-life exploits of Hillary, who in 1953 became the first person to conquer Everest; Edward Whymper, the 19th-century mountain climber who was the first to reach the Matterhorn's summit; and Fridtjof Nansen and Ernest Shackleton, explorers of the North and South polar regions.

"I always had my eye open for a favorite adventure," Fossett said.

Mountains became a fascination for him at age 5. He began climbing at 11.

"It's an ingrained desire," he said. "The fact that I wasn't active in competitive sports made me focus on it. Mountain climbing is perhaps the purest of achievement sports. It's very direct. You must reach the summit. No matter how many times you get there, you still enjoy it."

Eventually, Fossett decided he wanted to be associated with what he considered monumental achievements -- swimming the English Channel, running the Boston Marathon, scaling Everest.

By the time he graduated from Stanford with degrees in philosophy and economics, he was ready to try. That summer, 1965, he traveled to Turkey and, like Lord Byron and the legendary Greek Leander, swam the Dardanelles.

Grad school in business administration and the dog-eat-dog world of commodities brokering injected pragmatism into his life, but still he foraged for fantasies. He drove briefly on the Formula Atlantic race-car circuit, worked out in a luge -- a lightning-quick one-man sled -- with the U.S. Olympic team, skied cross-country in the 10 national races of the World Loppet League, and, of course, climbed mountains.

In his Chicago condominium, Fossett keeps a file of adventures he hopes to have. The Everest climb is still on the list, along with a trip to the South Pole.

"At one time I thought I would drive in the Indianapolis 500," Fossett said. "I was in auto racing then. But I dropped out. It was too expensive then. Now, it's too time-consuming."

This summer Fossett spent most of his free time preparing for the Everest climb. The mountain rises to 29,028 feet above sea level. At that altitude the air is so thin that most humans can barely breathe. Along with usual hazards of avalanches and extreme cold, Fossett faces the prospect of altitude sickness, the most severe forms of which involve potentially deadly collections of water around the brain or in the lungs. The only way to overcome these dangers is to live at high altitudes until your body adjusts.

Each Friday afternoon Fossett boarded a leased jet at Meigs Field and flew to Beaver Creek, where he spent the weekend jogging, cycling and climbing in the Rocky Mountains. A routine day included hiking and running 22 miles of peaks and valleys in five hours.

"Typically I'll get four hours a day of strenuous exercise out here," Fossett said, sitting by a giant stone fireplace in his Colorado manse. "I run to and from work in Chicago, but going uphill here is much more concentrated than running on the lakefront. It's also 8,000 to 12,000 feet {above sea level}, so you get used to some altitude."

Fossett's regimen is grueling. But there is little chance it will turn him into some svelte Adonis.

"I'm always a couple of pounds overweight," he said. "I don't pay too much attention to diet."

But endurance sports, especially mountain climbing, rely on experience and pace as much as physique.

"You're talking about being able to sustain yourself over days and weeks," Fossett explained. "A speed athlete can go into the mountains and burn out quickly. That's why experience is so important. It's acquired over a period of years. You can't just go out for two months and train to climb a mountain."

Having said that, the millionaire options trader hopped in his Ferrari and drove to the base of a nearby ski run.

There was no snow on the ground, only a steep slope of loose rock and grass. Fossett wound his way up, zigging and zagging along a path of least resistance. With each step his taut, muscular calves flexed. Soon, the midsummer heat began to extract its pound of flesh. Sweat poured from Fossett's body and soaked his gray-and-white knit shirt. His breath came in loud grunts. He picked each foot up and with agonizing deliberation set it down in front of the other.

"This gives you a little rest but keeps you going," he explained.

The gait created a continuous, if choppy, rhythm:

Step, pause, roll forward on the ball of the foot, push.

Step, pause, roll forward, push.

He moved in what seemed like slow motion.

"I'm heavy," Fossett had admitted earlier. "Speed is not my strong suit."

Neither, on occasion, is coordination.

The day before, while training on his 10-speed bicycle, he had applied his brakes but couldn't pull free from a clip that locked his foot to the pedal. He crashed over sideways, just like that character on the tricycle on the old "Laugh-In" show.

As passing drivers chuckled, Fossett picked himself up and continued his workout. The spectacle he created didn't embarrass him, because he knew he would have the last laugh. Within himself he has found a survivor, a dumpy guy too fat and clumsy, perhaps, to win but skillful and determined enough to finish.