Running the London Marathon is hard enough but doing it 36 hours after a professional boxing fight just sounds like madness.
But that is exactly what Carshalton's Ricky Boylan will be doing this weekend.
On Friday, he fights a six-round fight at the Britannia International Hotel in Canary Wharf and, having had Saturday to recuperate, will take on the 26.2 mile London course on Sunday.
"I have got to be crazy," said the 24-year-old, who is running for DEBRA, a charity working on behalf of people with the genetic skin blistering condition Epidermolysis Bullosa.
"I have always wanted to do a marathon and signed up to it before the fight was arranged.
"But I had said I wanted to keep busy so I accepted the fight and, hopefully, I can recover on the Saturday and get a good time on Sunday.
"I would like something like three hours, 45 minutes, I would be happy with that considering I have boxed two days before.
"It's not the fight that will take it out of me, it's all the training leading up to it. Most people will be resting this week but I was training and running for my fight until Wednesday."
Boylan has an impressive record in the ring since turning professional with seven wins from seven and is gearing up to a title fight.
"It is important for me to be busy this year and each fight I am having I am learning," he said.
"Hopefully, I can keep it going and before too long I should be fighting for a title of some sort.
"This is another six-rounder and then I will have an eight-rounder after that and, if I win them two, there should be a fight for a title."
To donate to Boylan's cause, visit justgiving.com/rickyboylan1.