Double Olympic champion James Cracknell has decided to retire from rowing after a glittering career.
Cracknell admits it was a difficult decision to end his career
The 33-year-old left the sport after winning gold in Athens in 2004 but recently returned to row across the Atlantic with TV presenter Ben Fogle.
Cracknell said he had realised he had lost his "hunger for rowing".
"In our sport you have other people's dreams in your hands. If you're not committed you're going to let them down as well as yourself. That's not fair."
He had been thinking about his decision since the Athens Olympics, he said, but had made his mind up while he was crossing the Atlantic.
"When I was out there I realised that I am intensely competitive, but I felt if I was going to go back to rowing it was because I really wanted to compete at something rather than because I really wanted to row again. So I realised I should probably find something else to compete at.
"The chance to do something else is really exciting and if I carried on for another two or three years I may not have the chance to do that."
Cracknell said his feelings had changed over the months since the Athens Olympics between wanting to compete in Beijing and a desire to take on different things.
"My decision to retire from rowing has not been easy but it is made slightly easier because I'm pretty satisfied with what I have achieved," he told the Daily Telegraph.
"The two Olympic golds and six world titles may go down as the defining statistics of my career, but I am more proud of making the most of my limited talent and never refusing to believe I wasn't going to win at the Olympics, even after missing the 1992 and 1996 Games.
"Much of me would still love to race at Beijing and whatever I'm doing in 2008 I will wish that I was in that boat.
"Perhaps it would have been easy to go back to the comfort blanket of full-time training but that would have meant avoiding the risk of attempting to succeed at something other than rowing."
Cracknell missed the 1992 Games in Barcelona because of injury and he also missed out four years later when he contracted a virus the day before he was due to race.
But he made it third time lucky in Sydney in 2000 when he and team-mates Steve Redgrave, Matthew Pinsent and Tim Foster won gold in the coxless fours.
He repeated the feat four years later in Athens with Pinsent, Ed Coode and Steve Williams.