Boxing
United States
Age: 21

As a kid in Cincinnati, Warren had a choice: hit the gym, or maybe end up in jail. "The older guys would go around, punchin' on people for no reason," he says. "There were shootings, killings. That's when I realized that boxing was good for me." At 17, Warren was the youngest male member of the U.S. team in Athens, and lost in the first round. Now, he's the flyweight favorite after winning the world title last year. Warren is the first U.S. boxer to compete in back-to-back games in 32 years. Why not go pro like his colleagues? "Gold medal," he says. "Gold medal. That's all that's been on my mind. I know how the Olympics feels. I know the ring, I know the judges, I know how to fight for the judges. I'm ready."