Alan Rosser underwent a heart transplant at the renowned Harefield Hospital in 1994 after being diagnosed with cardiomyopathy.
"The doctor said I was unlikely to see Christmas, but that I had one chance – a transplant," said Alan.
"For 16 years my lifestyle was as it had been before, then my body started rejecting the organ, but I have been given new drugs and as I long as keep taking them I'll be ok.
"I'm 79 now and I hope my story gives hope to others in the same situation I was in, that all is not lost – you can be restored back to health."
Dan Rosser, who runs a pharmacy in Church Street and another in Bristol, took on the Welsh Three Peaks challenge in aid of Harefield.
"My uncle was the person that got me into pharmacy – he was always taking so many tablets when I was young," said Dan.
"From the age of 10 I lived with my aunt and uncle, so when I got the chance to do the challenge I decided to do it for the hospital."
Dan trained by climbing a different mountain each weekend in the build up to the main event – climbing Snowdon, Cadair Idris and Pen y Fan all on the same day.
Collection tins in his two shops helped bring in £1,000 in sponsorship money, which has since been sent to Harefield.