Gymnast Shawn Johnson ends comeback, retires (AP) The knee injury that sparked Shawn Johnson's comeback put an end to it, too. The Olympic gold medalist announced her retirement Sunday, saying repeated setbacks with her left knee made contending for a spot at the London Games impossible, and left her fearful she was putting her long-term health at risk. "It just little by little gets worse and worse," Johnson told The Associated Press. My body is to the point where I need time to rest and retire so I can be healthy for the rest of my life. It's hard to wrap my mind around. Gymnastics has been my entire life, and now it's no more. Pictures: Shawn Johnson Complete Coverage: The London 2012 Olympics Her announcement, four days before the start of the U.S. gymnastics championships, brings a melancholy close to a career that took her from Iowa to Hollywood, with a few world titles, a trip to Beijing and an Olympic gold medal sprinkled in between. "It's just been a fun road with Shawn," USA Gymnastics president Steve Penny said. After winning four medals at the 2008 Games - only Michael Phelps, Natalie Coughlin and Nastia Liukin left Beijing with more - Johnson took the next two years off. She won "Dancing with the Stars" and, with her bubbly personality and girl-next-door looks, became a bona fide celebrity. She left the door open to a return for London, but it wasn't until she blew out her knee in a January 2010 ski accident that she realized she still wanted to compete. Her first stop after the doctor's office was her gym, where she and coach Liang Chow began plotting her comeback. The long layoff would present enough of a challenge, but her knee made it that much more difficult. She had torn the ACL, MCL and meniscus, along with her hamstring, and it never returned to full strength. She made the team for last year's Pan American Games, where she helped the Americans win the team gold. But when she tried to increase her training over the last few months to get ready for London, her knee would not cooperate. She couldn't do the number of repetitions she needed, and there were days she couldn't even work out because the knee would be so swollen. "That was a hard, hard thing," Chow said of watching Johnson struggle. Finally, Chow sat Johnson down and said they needed to be realistic. She couldn't put in the training she needed, and she was looking at an entire knee reconstruction if she kept going. It's been a really hard decision. How can you tell yourself, 'No, I think it's time to say it's finally done?"' said Johnson, 20. I'd like to be 30 and have kids and run around with them. It became more about my future life than this future one moment. I'm looking at the bigger picture of things. But it still hurts. It's weird, for the first time in my career I came up short. But I feel like I succeeded as well," said Johnson, who listed making the Pan Am team after the knee injury as one of her proudest accomplishments. It almost came too easy the first time. It was a humbling experience this time around. Johnson was once billed as "the next Mary Lou," a fresh-faced kid from West Des Moines, Iowa, who could jump and dream. Famous is the story of Chow trying to get Johnson her first invitation to a national team training camp. Unsolicited, he sent national team coordinator Martha Karolyi a highlight tape and promised that "this kid will help the U.S. team." Based on the pure moxie of the move, Karolyi couldn't help but take a look. Chow turned out to be right. Along with her gold on balance beam in Beijing, Johnson won silvers in the all-around, team competition and floor exercise. Her all-around title at the 2007 world championships was at the time the fourth by a U.S. woman, and she also led the Americans to their third team title and took gold on the floor exercise. Shannon Miller is the only other American to win three golds at a single world championships. Her performance at worlds was the exclamation point on a winning streak the likes of which is rarely seen in gymnastics. Johnson won every event she entered in 2007, her first as a senior, establishing herself as one of the poster kids for the Beijing Games. It also set up a compelling, yet friendly, rivalry with Liukin. "Shawn will always hold a special place in gymnastics and my heart," Karolyi said. She always showed the joy of doing gymnastics. Indeed, it was that personality that made Johnson so popular with both gymnastics fans and folks who think a floor is something to sit on. She was always cheerful, frequently flashing a megawatt smile almost as big as she is, and delightfully unaffected. As a way of saying thank you to Chow and his wife and co-coach, Li Zhuang, Johnson learned how to write their names in Chinese and surprised them by putting the characters on the sleeves of her leotard for the 2007 U.S. championships. After she finished second to Liukin in Beijing, Johnson was among the first to embrace her teammate and congratulate her. If she was disappointed, she wasn't going to spoil Liukin's accomplishment by showing it. "We're going to truly miss her," Chow said. But we realize life is going on and we want to wish her the very best. Johnson said she made her decision Friday, then spent the next day telling those closest to her. But no matter how many times she said the words, they hadn't quite sunk in. She imagines that will change over the coming months, as she watches the rest of the U.S. women fight for a spot on the Olympic team and experience everything she did just four years ago. She still plans to attend nationals and the Olympic trials; her training partner, Gabby Douglas, is a favorite to make the London team. And she plans to go to London, where she promised to be "the greatest cheerleader in the stands." Her autobiography, "Winning Balance," is being released Tuesday, and she plans to go to college in the fall of 2013, though she hasn't settled on a school. Beyond that, however, Johnson's not sure. "I'd normally say I have practice at 2:30," she said. I don't know and that's hard. I'm at a point where I don't know what's next. Though it may not have ended how she imagined or hoped, Johnson said she has no regrets about her comeback. She felt she had gotten "off track" in the two years after Beijing, and returning to gymnastics reminded her of what was really important. "The comeback has made me 10 times more a stronger person than I ever was," she said. The past two years in gymnastics brought me back to the real me. I feel like no matter where I go next, I'll be more level-headed about it. And do what's right for me.