His mom, Michelle Roybal, remembers thinking he looked like the Peanuts character Pigpen when he'd hit a baseball and kick up dust when using his arms to swing and scoot his upper torso down the baseline.
But baseball wasn't his sport. As soon as he tried sled hockey, at age 7, he found his passion.
"That was it," says Roybal, who's now 15 and a sophomore in high school in suburban Chicago. "It's all I wanted to do."
Roybal joined a youth sled hockey team in the Chicago area known as the Hornets. The participants, who can't use traditional skates because of varying disabilities, sit in sleds and use two shorter sticks to propel them around the ice and to control the puck.
By age 12, Roybal was so good that he started playing with an adult team—a big challenge for a kid, since the adult game is so much more physical.
But J.J. O'Connor, co-founder and general manager of the Hornets, says his coaches saw Roybal's potential early on.
"I'm telling you right now," one coach told O'Connor, "this kid has the potential to be the best that's ever played the game."
Now Roybal is the youngest U.S. Paralympic athlete—a member of the national sled hockey team headed to Sochi, Russia, to defend its gold medal from the 2010 games. The team is the subject of a PBS documentary called "Ice Warriors" that begins airing Monday.
O'Connor, who lost use of his arms and legs after a hockey accident when he was a teen, said he feels like he's living vicariously through Roybal.
"Everybody dreams of representing their country and being an Olympian and winning a gold medal," O'Connor says. "That's something that I wasn't able to do. And this is the next best thing."
Though his mom had had several ultrasounds when he was pregnant, Roybal's parents didn't know until he was born that he had no legs. But after some occupational and physical therapy, they say he lived life as much as he could like any other child.
His dad, Robert Roybal, says they've pushed him a lot to be independent—"pretty hard sometimes." But their son says he appreciates now that many people he encounters respect his independence.
In many ways, he says, he's "just another average teenager," he says—one, he adds, "who's lucky enough to go to the Olympics."
Ice Warriors preview: http://www.pbs.org/wgbh/medal-quest/video/detail/ice-warriors-short-preview/