Remember the President's physical fitness test? Most American kids had to go through it to test their strength in P.E. class. You'd think Horton, the son of a strong athlete, would ace it. Not so.

Horton hardly mustered 15 push-ups. When asked to do a dip, he couldn't do a single one.

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"I shook like a leaf," he says.

You've heard the cliché about the guy who's picked last on teams at recess. Well, that was Tony Horton, who was born in Rhode Island but raised mostly in Connecticut. "P.E. class was this horrible, embarrassing thing," he says.

Horton went on to play high school football, if you can call it that.

"I was a tackling dummy," he says. "I was keeping stats, holding my helmet. It was humbling and embarrassing. There were athletes and then there was everybody else. They just thought the rest of the kids were pathetic."

If you watch or use the P90X videos, which consist of several hour-long workouts designed to "confuse" muscles with their variety, you see a guy who has obviously overcome all that. But if you listen carefully to what Horton is saying, you find the key to his success. Everyone thinks the reason to go through 90 days of torture is to look great. That's part of it. But a lot of the motivation comes from Horton himself, who understands that most of the people using his video are much more like the high school Horton rather than Horton the hulk.

"My middle name is Sawyer," he says, "but I always said it was 'Scared.' I was petrified a lot."

So he understands many of his viewers are also scared. They can’t do 50 push-ups, certainly not 10 pull-ups, and they probably can’t get through Day 1 of 90 without frustration, exhaustion, and some self-loathing.

Hence the now-iconic phrase, "Do your best and forget the rest."

"That all stems from my experience when I was younger and I couldn’t do things," Horton says. "People [using the video] understand they can hit the pause button. They don’t have to do the exercise the way they see it."

That's a far cry from most exercise videos, where everyone on the screen is in perfect shape and smiles through the workout as if it's a pleasure to torch every muscle in your body. In the P90X videos, demonstrators can be seen doubled over and even losing balance. No, they’re not out of shape by any means. But they all seem fairly regular. Horton chides one about his (relatively) advanced age. One actually works out on a prosthetic leg.

In a phone interview, Horton tells a story about training singer Tom Petty: "I put a dumbbell in his hand and he nearly fell over," Horton says. "He pretty much died after 30 minutes. But Tom Petty was in the same place I was [in high school]. I was thinking, 'What do I need to do to inspire him?'"

That's not really how most trainers think. Many are in it for the money, or for the false sense of power.

"When I look at a lot of trainers, and I see their style of trying to motivate people, I'm just blown away," Horton says. "People are screaming at you. The person putting you through this discomfort better be understanding or you won’t come back. You have to be a great communicator."

Horton is certainly that. His background is not so much in fitness but in stand-up comedy. That too, he says, is because of his awkward childhood.

"I used humor as the only way to get through life," he says. "I had a speech impediment. I had the attention span of a squirrel on crack. I moved seven times as a kid. I probably had some level of depression, for sure."

Weightlifting was something he got into because he liked the class he took at the University of Rhode Island. He thought the coach had a good sense of humor, and he looked up to him. It went from there.

Horton moved to California to try to make it in entertainment and he wasn't too proud to, say, get in bed with a rock queen or don a horrendous bare-midriff outfit as a pitchman for Ab Works.

Even when he brags -- mentioning the fact that he did 35 straight pull-ups in front of a group of American soldiers -- he couches it in feigned weakness: "I thought I was going to hurl."

Truth is, he's got lots to brag about. He's sold more than three million P90X sets since the program launched in 2004. He's made his brand a household name -- in a good way. Even Bruno Mars has sung about P90X.

Now there's a sequel coming out: P90X2. Can Horton keep it up? His 10-minute trainer videos were different from the much-longer P90X originals, starring a hot model who looked incredible before, during, and after every workout. Now the P90X2 videos are "for fit people who want to become superfit." He's dropped the cardio segment, which was for people who couldn't quite keep up with the hellacious Plyometrics jump-training workout. And he's added "Plyocide," which, well, you can imagine how hard that must be.

Can Horton appeal to the elite fitness buff -- the P90X "graduate" -- and still be accessible to the spare-tired suburban dad? What can you do after you've started a revolution? That's a question not even Bon Jovi could answer.

Tony Horton is now a star. He is rich and famous. He has a huge outdoor training facility in his backyard. He says, "I want to peak in my 90s," and he just might. He's a long way from the scared kid he was in Connecticut nearly 40 years ago.

But he knows he can’t go much farther unless that scared kid comes along with him.