25 fittest guys

FIT FACTOR: Zupan, the 2004 quad rugby player of the year, is good enough to have snagged a Reebok endorsement deal. He's also tougher than almost any other athlete we know--period. When asked if he's afraid of getting hurt on the court, he once answered: "What's the worst that can happen? I break my neck again?"

The Stand-up Guy

Dane Cook, 34

Boston

MF-APPROVED BECAUSE: More than a million people have gotten quite the ab workout from Cook's ripped-roaring second comedy album, Retaliation, which debuted at No. 4 on the Billboard charts, making him the highest-charting comic of the past 25 years. Next up: movies with both Jessica Simpson and Steve Carell, and a multiproject development deal with HBO.

FIT FACTOR: The great Dane has said his physically demanding shows are "a total-body workout. Plus, right after the show, I come offstage, leave the show, and run around the club until I puke Now, that's what we call a serious commitment to exercise.

The Soldier

Brad Rogers, 34

Hebron, Ky.

MF-APPROVED BECAUSE: When a fellow soldier was killed in Iraq last year, Staff Sergeant Rogers made sure his death was not in vain. Rogers, who felt the tragedy could have been avoided if the soldier's vehicle had featured proper armor, started a letter-writing campaign to the media and politicians that resulted in his unit receiving better equipment, a feat that has almost certainly saved countless American lives.

FIT FACTOR: Already a fitness buff, Rogers says he worked to become especially cut while serving overseas. "Truthfully, I worked out more [in Iraq] than back home," he told MF recently. "There's not much else to do in your downtime. No family, no TV--so working out became a huge form of entertainment."

The Cowboy

Heath Ledger, 27

Perth, Australia

MF-APPROVED BECAUSE: He's been the hot new Aussie in Hollywood for a couple of years now (sorry, Russell), which made his decision to play Ennis in Brokeback Mountain all the more courageous. "I like building obstacles," Ledger has said, "and then destroying them."

FIT FACTOR: When the stars align, Ledger loves nothing more than to take to the waves and surf. But having a career that places him in such demand means he mostly hangs out in his Brooklyn, N.Y., home with his fiancee, sexy actress Michelle Williams, and their newborn baby girl. "I'm Mr. Mom" Ledger recently admitted. "Every day, I wake up and prepare two breakfasts."

The Swinger

Roger Federer, 24

Basel, Switzerland

MF-APPROVED BECAUSE: Not only is he the best tennis player of his generation, he's already one of the best ever. At just 24, Federer's been perched atop the ATP rankings for 111 consecutive weeks (as of press time), the third-longest streak in history.

FIT FACTOR: "Strength training, footwork drills, cardio work, and flexibility contribute to my being in peak shape" Federer told MF. "It's important to be well rested and hydrated, not just during tournament weeks, but all season long. I spend a tremendous amount of time working on recovery, as the season is extremely long, and being able to endure it is paramount to my overall performance"