Brock Walker is an accomplished motocross rider. Especially when you consider that he's only 13 years old.

Ask him how many national titles he has to his name, and he guestimates.

"Around 9."

He's lost track. But when you've been riding since 2, and racing since 3... well, some of those wins might've come before he was actually forming memories.

His father hasn't forgotten.

"Little dirtbike with training wheels on it," Brian Walker says wistfully.

Wait. They do training wheels on motocross bikes?

"Yes, on the very little bitty 50 [CC]s, you can get 'em with training wheels," Brian said. "The training wheels didn't last long."

No, they certainly didn't.

Danger is just part of this sport. Brock said his parents are used to it by now. But his grandparents...

"My grandma gets really nervous."

What do you tell her?, I asked him.

"It'll all be okay."

Has that ever not been the case?

Brock sheepishly smiles, knowing what he's about to say is a half-truth, at best: "One time, yes sir."

Up next for Brock is the biggest race of the year -- the Loretta Lynn Nationals in Tennessee. The cream of the crop from around the country -- the best 42 in each age group -- race there every year. Last year he finished ninth. This year, though, he's stepping it up a notch. He'll be the youngest rider, in a more difficult division.

"You just gotta get faster, and train as hard as you can," Brock said. "You put sweat and tears into this."

He's focused. But also mature in his focus.

"It's always to win. But, as long as I try my hardest and don't give up, that's what counts."

And he's got big things on the horizon.

"After Loretta's here, in August, we could be on big bikes, at a young, young age," Brian said. "But the goal is, hopefully, by 16, we'll turn pro.

"He's just got a gift in this sport, and it's just really neat to watch."

Just 13 years old -- and still more accomplishments to come.