Carlos Leon, 24, is a member of the U.S. Paralympics Track and Field team.

I thought it would be all business when Carlos Leon was training for the Beijing Olympics at the Lakeshore Foundation in Birmingham, Alabama. No talking. No laughing. I was wrong. At first I gave Carlos his space when he was lifting and doing cardio. But, Carlos is full of soul and spunk even while he’s doing his serious training. He even invited me to join in (although my weights were much lighter than his).

From a headshot or the right camera angle, you’d think Carlos is competing in discus at the Olympics. But, he’s the first to emphasize that he will be in the Paralympics. The 24-year-old Iraq veteran became a quadriplegic while he was diving in Hawaii, celebrating being back in the states.

His physical setback has not squandered his dreams. He’s focused enough to ban his parents from visiting him at the training facility where he now lives. But, he’s humble and fun enough to let a camera crew in to hang out with him days before he’s set to compete.

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Mike Day, 23, is a member of the U.S. BMX Olympic team.

BMX stands for Bicycle Motocross. This summer BMX is adorned with the Olympic rings. It’s the first time BMX has been included as an Olympic sport. Mike Day couldn’t wait for the day that was the case.

Mike, now 23, won his first race on his ninth birthday. He turned professional in 2002. His goal wasn’t to go to the Olympics though, since they only recently announced Olympic BMX trials. Initially, all he wanted was to gain the respect of his friends’ families. Mike remembers one friend’s dad saying, “Watching you guys back in the day, I never would’ve dreamed BMX would have taken you this far.”

Now that it has, Mike is ready for the gold. He looks at every day, and all the training that comes with it, not as a burden but as fun. Mike simply says, “I have the best life ever.”

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Taraje Williams-Murray, 23, is a four-time national judo champion.

Taraje Williams-Murray knows exactly where he’s going to eat when the Olympics are over. He knows the cooking he’s going to do to gain back 25 pounds. He knows all about the lazy Sundays he will have with his girlfriend and family just vegging out.

But he’s putting that all aside for now in the name of sacrifice, which is basically the first word out of 23-year-old Taraje’s mouth these days as he prepares for the Beijing Olympics. He’s a four-time national judo champion and was on the U.S. judo team in Athens four years ago. He knows exactly what kind of sacrifices he’s making with 16-hour training days with strict workouts and a strict diet. It was all the subject of his documentary, “Beyond the Rings”.

Taraje has been competing in judo since he was eight years old. “The pinnacle of any judoka is the Olympics,” he says. He knows all the fun he could be having if he wasn’t training, he can wait for that but he can’t wait to compete.

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Sada Jacobson, 25, is currently ranked the #1 Women's Sabre Fencer in the world.

When Sada Jacobson tells people she’s a fencer, without a flinch most of them will “air poke” her with their finger. She laughs, “It’s not like I can fight them with my finger!” She takes their misconceptions of cartoonish medievalism with levity.

But there isn’t much humor when she’s training in the gym for the Beijing Olympics. It’s a daily regimen: cross-training, cardio, conditioning, lifting, icing, lunch, footwork, strategy, and of course, hours of fencing. Sada, 25, is currently ranked #1 in the world for women’s sabre, but there’s no time for that to go to her head.

Make no mistake, Sada wants the gold. She took the bronze at the 2004 games. She doesn’t fight off the mat, but this time she’s focused on a tough fight for what she left behind last time.

Update: Watch the CNN.com Live interview