Aug. 18 (Bloomberg) -- The little boy who bedeviled his classmates and was told he would never succeed turned into the greatest gold-medal machine in the history of the Olympics.

Michael Phelps says he swims because it's fun and he wants to change the sport. He staged an eight-act promotion for that quest in the pool at Beijing.

The 23-year-old from Baltimore won more gold medals in a single Games than any athlete in history with his eighth yesterday, pushing the record for career golds to 14. Not bad for a troublesome kid who helped channel his energy by reading newspaper sports pages.

``It really shows that no matter what you set your imagination to, anything can happen,'' Phelps said at a news conference. ``If you dream as big as you can dream, anything's possible.''

His performance in Beijing's Water Cube was the focus of an Olympic swim meet that produced 25 world records, seven by him.

``There is nobody in any sport who can win like he wins,'' said Eddie Reese, head coach of the U.S. Olympic swim team.

The records in Beijing make Phelps the greatest Olympic swimmer but not the greatest Olympic athlete, said David Wallechinsky, vice president of the International Society of Olympic Historians.

``I give my nod, jointly, to Paavo Nurmi and Carl Lewis,'' Wallechinsky said in an e-mail of the two former track-and-field champions, who shared the old career gold-medal record of nine with swimmer Mark Spitz and gymnast Larissa Latynina.

Ratings Boost

The impact of Phelps is being felt far beyond the arenas and stadiums of Beijing.

Swimming finals were moved to the morning so his medal races could be shown live on U.S. television in prime time and ratings on NBC jumped 13 percent from Athens in 2004. International Olympic Committee marketing chief Gerhard Heiberg said the bigger audience may mean the General Electric Co. unit will have to pay more if it wants to renew its rights deal after the next Games in London in 2012.

Phelps said the spotlight he attracts is a step toward getting more people into the pool.

``My big goal is to change the sport of swimming, for the kids coming up in the sport and for the sport in America,'' he said.

Ratings jumps and promotions -- such as the Baltimore Ravens showing his eighth race on the stadium screens after a National Football League preseason game -- ``show that my goal is starting to happen,'' Phelps added.

Lesson Learned

Michael Fred Phelps was born on June 30, 1985, the youngest child of a police officer and a teacher. They divorced while he was young and Michael became a problem in school, chattering, bothering classmates and bringing home a lot of notes.

``My mom and I joke that I had a teacher, I think in middle school, who told me I'd never be successful,'' Phelps said after breaking Spitz's record.

Phelps was diagnosed in elementary school with Attention Deficit Hyperactivity Disorder, or ADHD, described by the U.S. National Institutes of Health as among the most common mental disorders in children. He took Ritalin as treatment until abruptly telling his mother that his friends didn't use medicine and he'd handle it himself.

About the same time, he started swimming at the North Baltimore Aquatic Club, where his sisters competed. He also met Bob Bowman, the club's new coach. They are still a team.

Phelps made his first big splash at the 2000 Olympics as the youngest male competitor since 1932 and finished fifth in the 200-meter butterfly. He became the youngest man to break a world record, in the same event, at 15 years, 9 months. That list is now 32 records long -- one behind Spitz's record.

Broken Wrist

He won six golds at Athens in 2004 and added seven at the 2007 world championships. He also made three trips to China for sponsors, learned Mandarin and got to see the Olympic facilities. His agent at Octagon, Peter Carlisle, wanted to make China feel like home and open doors in the world's biggest market.

The path to the record books has had potholes. Phelps was charged with underage drinking after the Athens Games in a traffic stop in Maryland. He apologized and said he made a mistake. Last October, he broke his wrist getting out of a car at the University of Michigan, where Phelps is taking sports- management courses and swimming for Bowman at Club Wolverine.

His coach and agent say he's grown up, working with charities such as Boys and Girls Clubs of America and Pathfinders for Autism. He's going from Beijing to Baltimore to spend time with family, friends and his English bulldog, Herman.

London is next. He says he won't be swimming after he's 30.

`Too Difficult'

His one race in Beijing that didn't produce a world record epitomized Phelps's strength and desire, according to his rivals.

Phelps overcame a half-body-length deficit in the final 25 meters to nip Milorad Cavic of Serbia by 0.01 second for the 100-butterfly gold medal on Aug. 16. That tied him with Spitz, who called the race ``epic.''

``For Phelps, it's not too difficult. For me, it's very difficult,'' said Ian Crocker, the world record-holder and U.S. teammate, who finished fourth. ``His body allows him to still have strength when he's tired. He can do what he wants to do.''

What he wants to do most is win.

``I hate to lose,'' the gold medal king said.

To contact the reporter on this story: Larry Siddons in Beijing at lsiddons@bloomberg.net.

Last Updated: August 17, 2008 12:11 EDT