Mark Steines, 44 - The Anchor
Injuries may have derailed the Entertainment Tonight anchor's football career, but the former fullback still lives out his fantasy on PlayStation. "I started playing Madden while I was on my elliptical trainer, and 45 minutes of cardio flew by," he says. "I've played endless seasons, won numerous Super Bowls. My wife always asks me how my fake Raiders are doing." Steines and his wife love running up a set of steep concrete stairs-84 total-near their house in Santa Monica, Calif. But the couple also work out at home, in front of their two sons. "We want to set an example for our kids." After 13 seasons co-anchoring ET, Steines's definition of fitness has certainly evolved. "It's all about balance. To me, it's not just about hitting the gym, it's also about being a father and a husband and keeping a career on track for more than two decades," he says. "For me, that's true fitness."

Jimmy Smith, 30 & Doug Anderson, 26 - The Reality Badasses
Smith is a mixed martial artist known for grappling opponents to submission in under three minutes. Anderson is an Iraq War vet with only one fight under his belt. But nothing could fully prepare them for Discovery Channel's hard-hitting reality series Fight Quest, in which the pair travels to a different country known for its combat style-like Filipino stick-fighting or Brazilian jiu-jitsu-to train intensely and then take on a local in a no-holds-barred bout. "It's like a cage fight every single time," Smith says. So why do they do it? "For me it's personal," Anderson says. "I have too much pride to walk away from a fight."

Read More from Jimmy & Doug

Greg Plitt, 30 - The Mf Alum
Former Army Ranger Greg Plitt has come a long way since gracing the cover of MF in October 2005. After landing his first film role in 2006's The Good Shepherd, he can now be seen on television as the carpenter in HGTV's Designed to Sell and the new trainer in Bravo's Work Out. With just 4.8% body fat, Plitt credits a daily workout that consists of five-mile cardio in the morning and weights at 10 p.m. "The great thing about lifting late is you get home, slam a protein shake, and your muscles are relaxed and rebuilding throughout the night," he says. Plitt targets a different body part each day and finishes with 15 minutes of abs. Says Plitt: "I never schedule an off day."

Brady Quinn, 23 - The Understudy
Quinn may still be wearing a bit of a chip after sliding to the 22nd pick in the 2007 NFL Draft, but that's actually helped the 6'3", 235-pound QB stay focused as he waits his turn in Cleveland. "You have to use it as motivation," he says. "My job is to compete and start for the Browns and lead them to the playoffs." Relegated to second fiddle behind surprise star Derek Anderson, Quinn hit the gym hard this off-season. "Squats are huge," he says. He pauses for 30-50 seconds at different points in the movement to build stability and core strength. But, like any elite athlete, his routine changes regularly. "I'm big into med-ball throws and plyometrics," says the Notre Dame alum. Quinn makes no secret of his desire to start in 2008 and has done all he can to prepare for the challenge. Says Quinn: "As a competitor, you need to do something extra to gain that edge."

Read More from Brady

Amaury Nolasco, 37 - The Breakout
With the fourth season of Prison Break and three new films on the way, the busy actor can't afford to get flabby. While the gym bores Nolasco to death, it's a necessity. "You don't want to have to use doubles for shirtless scenes," he says. So he's picked up boxing with a former Navy SEAL trainer, in addition to body weight training, medicine ball exercises, and tons of ab work. "The show picks up about six months from where we left off [in the season three finale]," says Nolasco. "It was my personal choice for the udience to see a physical change in my character."

Ryan Sheckler, 18 - The Skateboarder
No one goes bigger, skates harder, or looks better on four wheels than the star of MTV's Life of Ryan. "I do skate a lot with my shirt off," he admits. "And I'm not trying to look bad, so working out has always been important to me." Sheckler started as a prodigy, winning a California championship when he was just 8 years old. At 13, he took home X-Games gold. Today he's more focused and fitter than anyone on a board. "I almost have as much fun working out as I do skating," Sheckler says. "Seeing your body change, getting more toned and cut, it makes a big difference in how I feel about myself and how I skate." This year, Sheckler's looking forward to winning the AST Dew Tour skate park event (again), taking home X-Games gold (again), and giving a little something back while he's at it. He recently donated his custom Range Rover to raise money for the Children's Cancer Research Fund.

Read More from Ryan

Chase Utley, 29 - The Batsman
Utley, the Philadelphia Phillies' second baseman, is one of the most consistent hitters in the National League. And he's still working to get better. After helping the Phillies rally from seven games back in September to win the NL East, he barely took any time off. "That was the shortest off-season so far in my career," Utley says. "My downtime was about three and a half weeks just to let my body recuperate." The California native mostly fuels up with fruits, veggies, and chicken, working out to enhance the power and quickness that led to his .332 batting average, 22 home runs, and 103 RBIs in 2007.

Read More from Chase