NEXT month, 25-year-old James Collins will cycle 15 miles to raise money for the Cystic Fibrosis Trust.
But what may seem a standard story of a young man raising money for charity will actually be the latest milestone of a remarkable recovery.
Five months ago James, who has the life-limiting disorder cystic fibrosis, underwent a double-lung transplant.
The life-saving surgery – made possible by an anonymous donor – has transformed James.
Where once he could barely walk ten metres without becoming severely short of breath, he now expects to complete the sponsored cycle on May 18 without running out of puff.
As well as raising money for a great cause, James, of Annsworthy Crescent, South Norwood, hopes his efforts highlight the life-changing potential of being a donor.
"I've written to the parents of my donor a letter," said James, who knows only that his saviour was a 40-year-old man.
"I thanked them for the lungs and for keeping me alive. Words cannot describe how much I have to thank them for.
"I wish there were more people like them to keep people like me alive."
As a baby, James nearly died several times and then struggled with the genetic condition, which affects the lungs, pancreas and liver, until the age of eight, when his health improved to a level where he could take part in physical activity, though not for sustained periods of time.
This remained the case until he was 23, when his lung capacity deteriorated dramatically, falling to 11 per cent in the months before his transplant.
"The thing with cystic fibrosis is that it just comes on like a tonne of bricks," he said. "It got to the stage where I couldn't walk ten metres without feeling like I was going to die. I was in and out of hospital for years."
Around a year ago James, a former pupil at St Joseph's college and primary schools in Upper Norwood, was told he would require a double-lung transplant.
Luckily his common blood type made finding a donor a realistic possibility. Even so, James spent six months on the waiting list before a match was found.
The surgery usually takes between seven and nine hours, but James's procedure was completed in three. "They said I was one of the quickest ever," he said.
"Apparently my body is very fit and easy to operate on. The way they put it was that it went exactly like the textbook."
You could say the same about his recovery. A few months after the procedure, James was back in the gym.
He now goes three times a week and takes his doctor's advice about keep fit extremely seriously.
James said: "I can't explain to you how good I feel. I only get out of breath if I push myself to the limit.
"The doctors described my lungs as 'prestige'. The surgeon said they expand so big they must be from an athlete. I don't know if he was saying that to make me feel better, but that's how it feels to me."
While James has been lucky, many others are not. Currently one in three people with cystic fibrosis die while on the lung transplant list. He hopes his story will encourage others to give the gift of life.
"The way I see it, by donating his lungs to me, my donor is still alive," said James. "Why not treat someone else to a lovely life like he did for me?"
To sponsor James, visit uk.virginmoneygiving.com/jamescollins1988