Washington, June 4 (ANI): Shawn Johnson has announced her retirement from gymnastics at the age of 20, but insists that she is excited to see what the future holds.

Johnson, who won four medals at the 2008 Olympics in Beijing, retired because of recurring knee injuries, ending her attempt to qualify for this year's London games.I still have the heart, drive, and desire to compete and help the USA at the London Olympics, People magazine quoted her as announcing in a statement on Sunday.

Unfortunately, it has become obvious that my left knee is not able to sustain the demands of gymnastics any longer, she said.All I can do now is gracefully retire and thank everyone who has believed in me and my journey, she said.

In addition to her gymnastics accolades, she had also won her season of 'Dancing with the Stars' in 2009.

Johnson added that she made the announcement now so the focus for the next three weeks will be on the incredibly talented gymnasts who are trying to make our 2012 Olympic Team.

She will still attend the Games to cheer on her former teammates.

The gymnast had injured her knee, for the first time, in a January 2010 ski accident and feared her long-term health would be at risk if she continued competing.

When she tried to increase her training in preparation for London, her knee did not hold up, and it was feared that continued training for the Games could mean a total knee reconstruction in the future.

It's been a really hard decision. How can you tell yourself, 'No, I think it's time to say it's finally done,' Johnson said.

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.

It's weird, for the first time in my career I came up short. But I feel like I succeeded as well, added Johnson. It almost came too easy the first time. It was a humbling experience this time around, she added.

The Olympian, who helped the American team earn a silver medal in Beijing in 2008, won silver in the all-around, silver on the floor exercise, and gold on the balance beam -to become the only U.S. woman to do so apart from Shannon Miller in 1996. (ANI)