Chrissie Wellington says she does not regret giving up her ambition to compete in the Olympic triathlon.
The 35-year-old Briton has won four world ironman titles - the event is not part of the London 2012 schedule, unlike the shorter-form triathlon.
"I made the conscious decision to choose ironman over the Olympics," Wellington told BBC Radio 5 live.
"I initially wanted to be an Olympic distance athlete, but I realised my talents lay in the longer distance."
Wellington became professional in 2007, at the age of 30, and won her first ironman world title in the same year.
The Suffolk-born athlete said she would like the longer form of the sport to become an Olympic event in the future.
"I'd love long-course triathlon to be part of it, although not necessarily the ironman distance," she added.
"That would be phenomenal. It would be a great spectator sport if it's organised properly.
"I don't think it'll happen in Rio , but perhaps some time in the future."
Ironman triathlon begins with a 3.86km swim, followed by a 180km bike ride and concluding with a full marathon.
Wellington will not be taking part in ironman events in 2012 but plans to compete in the Paris Marathon before cycling, via Hull, to the start line of the London Marathon, in which she also plans to run.
Her efforts will be in aid of the charity started by Jane Tomlinson, who died in 2007. Despite having terminal cancer, Tomlinson raised more than £1m for charities by taking part in endurance events, including the Florida Ironman in 2007.