Three-times Olympic gold medallist Ben Ainslie has said his body is "slowly letting him down" as he gets older.
But the 35-year-old sailing champion said he is still confident in his ability on the water and will draw on his previous experience ahead of this summer's Olympic Games.
Ainslie suffered defeat in the Sail For Gold regatta earlier this month as Giles Scott - who missed out on an Olympic place to Ainslie - beat him in the Finn class.
That prompted concern about Ainslie's prospects for London 2012 despite him having won the world championships just two weeks before.
The five-time Finn world champion was speaking as he showed the Prince of Wales around Weymouth and Portland National Sailing Academy where he is currently training.
Ainslie praised the team around him, who he said are keeping him on the water.
"My body in general is slowly letting me down as I'm getting older, but that is something that you have to deal with with getting older," he said.
"I guess I have more experience than the guys I'm racing against, but they don't have to deal with some of the issues I do physically.
"We have a great physiological team, so they've been a huge help in trying to get my fitness levels up and keeping me in one piece and getting me out on the water, so I'm confident we can do that."
Ainslie underwent successful back surgery in January at Frenchay Hospital in Bristol without which his presence sailing off Weymouth and Portland would have been in serious doubt.
But the competitor, who suffered from illness and a capsized boat as he lost to Scott in Weymouth, said he has no concerns about his level of performance.
The British sailor - the first torch bearer when the flame touched down at Land's End - added the competition in his class is wide open.
"It's a really open field in the Finn class, there's a number of really strong competitors," Ainslie said.
"There's probably any one of 10 guys that on the day could go out and win the races and be tough to beat, so there could be challenges coming from many areas.
"You have to be slightly open-minded about that, but generally in my experience you just have to worry about your own competition and do the best you can do and hopefully it will take care of itself."
Ainslie said his build-up towards the Olympics remains on course with just over a month to go.
"It's really getting exciting. As you can see there are so many international teams here training and preparing for the Olympics as they have been for a long time now," he said.
"But you can really feel the excitement and the tension building up and it's not long to go now, so these days are pretty critical and everyone is trying, as if cramming for an exam, getting as much time on the water to be as best prepared as possible."
Ainslie is seeking a fourth consecutive gold medal when he steps into his boat Rita in a month's time but said he tries not think about the medal win.
"It really doesn't matter what happened in the past or what could happen in the future, it is about the here and now, and trying to do well at this event, that's what personally I've been working at," he said.