2004 Olympic Champ Paul Hamm’s announcement today that he was returning to full-time training in hopes of making the 2012 Olympic Games, caught many gymnastics fans by surprise, but Hamm, just a few months shy of his 28th birthday, was upbeat and matter-of-fact as he talked about leaving his finance job at Chicago-based Breakwater Trading last week to move back to his hometown of Waukesha, Wis., and resume his gymnastics career.

“It’s for the all the reasons you expect,” Hamm says succinctly of the momentous decision. “I’ve been thinking about it ever since 2008.”

Hamm, who says he’s been working out semi-seriously for “six or eight months” at the UIC college facility in Chicago, hasn’t decided for sure where he’s going to train—right now he’s working out at Swiss Turners, his gym since childhood, but he’s planning a test stint at the U.S. Olympic Training Center in Colorado next month—but he’s certain of his goal: to compete in the all-around at the 2012 Olympic Games.

“He’s just got more to give,” agent Sheryl Shade tells Inside. “It’s that ‘unfinished business’ aspect. I think he’s been dying to tell people and get it out there, so he can just focus on training.”

Hamm, who says his he hopes to make next February's Winter Cup his first meet back, initially considered competing at this year's USAs, before a minor shoulder injury—Hamm says it was "just a tweak"—convinced him to take it slow.

Comebacks are nothing new for Hamm, who took a break from the sport after his second Games in 2004—where he became the first, and to date only, American man to claim all-around gold—to complete college (he graduated from Ohio State) and recover from the scoring controversy which, while completely beyond Hamm’s control, took at least some of the luster off his gold medal.

After his hiatus, Hamm looked better than ever at the 2008 U.S. National Championships, until a freak accident on his final event resulted in a broken hand and left Hamm struggling to recover in time for the Games.

In the end, it was a deadline that Hamm, despite a valiant effort, couldn’t quite conquer. He withdrew from the ’08 team, which would have been his third-straight Games, the day before the U.S. team departed for Beijing.

“There came a point in the gym when I just threw my arms in the air and knew this wasn’t working,” Hamm said at the time. “It was a really tough decision for me to make. It’s pretty deflating.”

That disappointment is a big part of why Hamm now wants to give gymnastics another go. “If you put yourself in my shoes you wouldn’t want to leave the sport like that either,” he states firmly. “No one would.”

As the only U.S. man to win the all-around at either the Olympic Games or World Championships (and he's done both) Hamm is, by far, the most successful male gymnast in American history. It is Hamm’s ability to remain dissatisfied, despite that astonishing level of accomplishment, that keeps him going.

“Yeah, yeah, I hear you,” says Hamm lightly, brushing off reminders of the astounding legacy he’s already established. “But …”

It’s that “but” that pushes Hamm. That has brought him back to the sport one more time, to try for one more Games. “I wouldn’t be doing this if I didn’t think I could be the best in the world,” Hamm states simply, without a hint of braggadocio.

Hamm’s limitless potential is a fact few would dispute. “He’s always been the guy I look up to,” 2009 National Champion Jonathan Horton says of Hamm’s return. “He hasn’t even competed yet and I already know he’ll be one of the best guys. Not one of the best guys in the U.S., but the world. I know it. It motivates me and just makes me feel like we’ve got a better shot of what we want to do in 2012. That ultimate goal of a [team] gold medal.”

If the training video, made by Hamm’s twin brother Morgan in May, and posted today on the brothers’ website, makingtheolympics.com, is any indication, Hamm is already well on his way.

“I’m just going to try and enjoy the process,” Hamm says. “After all, gymnastics is fun. It really is.”

UPDATED (7/21/10): To correct a typo that identified Jonathan Horton as the 2010, not 2009 National Champion.