A change of heart medication 12 years ago has given Sheffield's John McCormack a new lease on life, but he isn't the only one reaping the benefits.
Mr McCormack is running marathons to raise money for some special kids at the Sheffield Children's Hospital cancer ward.
His latest effort was to finish the Philadelphia Marathon. He crossed the line in five hours, which is an impressive effort given his heart problems.
Mr McCormack previously calculated the time he would take to run the marathon. He was under doctor's orders to keep his heart rate under 130 beats per minute.
The slower pace was ideal to take in the City of Brotherly Love's best views.
"It was a great sightseeing tour of Philadelphia," Mr McCormack said.
The money Mr McCormack has raised so far has gone into quite a large pot which is being filled by friends associated with his other passion - boxing.
Mr McCormack returned to the ring about 12 years ago, about the same time he took up running.
"They changed my heart medication and it changed everything," he said.
The Sheffield Boxing Centre at Hillsborough will on Tuesday hand over a cheque to the hospital for more than £42,000.
That takes the total amount raised so far to more than £300,000.
"It's a great figure," Mr McCormack said.
Representatives of the hospital will be on hand on Tuesday to receive the money.
Charity nights and Mr McCormack's marathons have combined to raise the funds.
Mr McCormack has come a long way since taking up running.
"My ambition in those days was to run a mile without stopping," he said.
He slowly progressed to half marathons, and then to the full distance.
His first love was boxing. He fought at London's York Hall - the "Wembley of Boxing" - three times.
His most memorable night in the ring was at Prince Harry's farewell before his military service in Afghanistan.
"I was marched by a bugler and everything," he said.
He was knocked out, and the first thing he saw when he came around was Sir Henry Cooper picking him off the canvas.
The owner of Enry's Ammer - his famous left hook - said "that was brave, son".
"Brave or stupid," Mr McCormack said.