Tagging along with his big brother, he would run down to the park to play ball against the older guys from the neighborhood in regular Sunday scrimmages.
He met a pitching coach who preached movement over velocity, and pretty soon Maddux was striking out those stronger teenagers. Nearly three decades later, he walked away from baseball Monday as one of the greatest pitchers to put on a uniform.
After 355 wins and 23 major league seasons, Maddux held a 30-minute news conference to announce his retirement on the opening day of the winter meetings - only minutes from his Las Vegas home.
"I really just came out here today to say thank you," he said in a ballroom at the swanky Bellagio hotel. "I appreciate everything this game has given me. It's going to be hard to walk away obviously, but it's time. I have a family now that I need to spend some more time with. I still think I can play the game, but not as well as I would like to, so it's time to say goodbye."
Next stop, the Hall of Fame.
Wearing a casual shirt and slacks, Maddux spoke softly on stage and never lost his composure. His family sat in the front rows, including brother Mike Maddux, the Texas Rangers pitching coach and a former big leaguer himself.
A large poster with photos of Greg Maddux hung behind the podium. He was introduced by agent Scott Boras, who said his client had a "model" career.
"Mad Dog threw a shutout today," said Bobby Cox, who managed Maddux during his dominant years with Atlanta. "Special, special guy. I get choked up talking about him."
Maddux leaves the game with four NL Cy Young Awards (1992-95) and a 3.16 ERA, especially impressive in the steroid era. The right-hander ranks eighth on the career wins list, with one more victory than Roger Clemens.
"I never changed," said Maddux, who turns 43 in April. "I think, hey, you locate your fastball and you change speeds no matter who is hitting."
He started to learn those lessons when he was about 15 from Ralph Medar, a local coach in Las Vegas who tutored Maddux in the fine art of pitching.
Before long, he was way ahead of the older kids.
"I just feel lucky to have seen it day in and day out for so long," Mike Maddux said.
In the big leagues, Greg Maddux thrived on smarts, movement and pinpoint control rather than overpowering heat. Throwing strikes and inducing grounders, he could get through eight innings on 80 pitches in under 2 hours.
At his best, Maddux featured a tailing fastball that froze left-handed hitters before darting back across the inside corner. With such sharp and unusual action, the pitch almost seemed to be a Maddux invention. One thing was certain, he mastered it like no one else.
"Precision. I don't know how to describe him other than that," Cox said. "He's taught a lot of guys to try to do it. But nobody does it like him. Nobody."
In Atlanta, Maddux teamed with fellow 300-game winner Tom Glavine and gritty ace John Smoltz to pitch the Braves to the 1995 World Series championship and an incredible string of division titles.
In fact, perhaps the biggest decision of Maddux's career also came at the winter meetings, when he spurned a higher offer from the New York Yankees for a five-year deal with Atlanta during the December 1992 session in Louisville, Ky.
An eight-time All-Star, Maddux won 13 or more games in 20 consecutive seasons - a streak that ended this year. He spent his final season with the San Diego Padres and Los Angeles Dodgers, finishing 355-227. His remarkable resume includes a record 18 Gold Gloves, including one this year.
Maddux broke into the majors in 1986 with the Cubs and pitched for Chicago again from 2004-06. He finished with 3,371 strikeouts, 10th on the career list.
"Everybody says he wasn't a strikeout guy. He was a strikeout guy," Cox said. "He'd get the strikeouts - first inning, man on third, one out, infield back, give 'em a run - believe me, he'd strike out the hitter."
Maddux was 8-13 with a 4.22 ERA during his final season. He made three relief appearances in the playoffs for the NL West champion Dodgers without allowing an earned run in four innings. Then, he filed for free agency amid speculation he would retire.
Plans for his farewell news conference were announced Friday, but Maddux made up his mind long ago.
"I think I decided actually two years ago, but I ended up playing one more year anyway," he said. "But I pretty much knew last spring training. I had kind of told some teammates and some people in baseball that this was going to be my last year. I don't think they really believed me, but I think I was telling the truth that time."
Maddux said he'll miss all sorts of things that came with major league life: poker games on the plane, golf outings on road trips, hanging out with his teammates.
He didn't rule out coaching in the future, but for now he's ready to stay off the field.
"Right now I think I want to take a year off and spend time with the family, do things that I have not been able to do because of baseball, and see if I like it or not," Maddux said. "I assume I'll like it, but I also don't know about being out of the game. I don't really know a whole lot about anything, but I feel like I know a few things about baseball. I'm going to miss it, and hopefully I won't miss it too much."