Joe Walsh, a father from Leeds, had been doing the washing up when he heard an appeal on the radio over a shortage of live kidney donors.
Deciding then and there he could 'share his spare', he went on to undergo an operation at Leeds' St James' Hospital last year.
He isn't special, or a hero, he says today. He too has gained from the giving of a gift which has helped someone else live a new life.
"I never realised that giving a kidney was something you could do," the 26-year-old from Farsley says. "I was just washing up, when I heard about it on the radio.
"It really struck me. What was clear was that it would cost me little, it would be a fairly straightforward operation. On paper, it was fairly routine.
"On the other side, it's someone else being to live their life fully. Perhaps even lifesaving for them."
Mr Walsh, a housing support worker in Bradford, works with homeless people with complex needs to support them into permanent accommodation.
He is a man of strong Christian faith, and wants to recognise that, in the way he lives his life. But he has gained too, he admits, in knowing that he has helped someone.
"As an altruistic donor, I was able to give my kidney to someone," he says. "And then their partner could give their kidney to someone else... It enabled two donations.
"It brought so much benefit to so many people. And it saves the NHS £200,000 per operation.
"I believe also in having a universal positive regard. I would be quite happy, whoever my kidney went to."
Mr Walsh lives in Bramley with wife Rio, 25, and daughter Myah, aged three. His family, he says, understand that this is a part of his character and his Christian values for life.
"We are all full of good and bad," he says. "We all have the capacity to be generous. And we can all be generous in different ways.
"For me, giving a kidney seemed very easy. Overall, I took a lot from it.
"I'm not a terrific person, I'm not a hero. We are all human, with different things to offer. It would be nice if it were a more normal thing to do."
'Share your spare'
He is speaking out today as part of National Kidney Month month.
There are almost 5,000 people in the UK on the waiting list for a kidney, and around 250 people die every year in need of one.
There are some risks with altruistic donation, and each donor is carefully assessed by hospitals and the Human Tissue Authority.
The operation, for him, says Mr Walsh, had been fairly straightforward. At any point, he could have changed his mind, and he was assessed psychiatrists ahead of his decision.
On the day itself, the doctors drew on his side with marker pen to ensure the right kidney was removed.
He was off work for six weeks after, to give himself time to recover.
"I feel just the same now as I did before," he says. "For me, giving a kidney was a fantastic experience.
"There isn't really an awareness. I do want more people to understand about altruistic kidney donation.
"If only a small proportion of the population would consider giving a kidney, it would easily end the waiting lists.
"What I'm trying to do is encourage everybody to think about what they can do to 'share their spare'. You can live a fairly healthy life with just one kidney."
Bob Wiggins, chairman of charity Give a Kidney: “Many people still don't know that any healthy adult can volunteer as a living donor and more than 800 people in the UK have now donated one of their healthy kidneys to a stranger, changing hundreds of lives for the better.
"Not only that, but someone stepping forward to donate in this way can potentially trigger up to three transplants, so kidneys from donors like Joe are incredibly valuable. Together this group of donors has already saved the NHS tens of millions of pounds over the cost of keeping the recipients of their kidneys on dialysis treatment."
Lisa Burnapp, clinical lead for living donation at NHS Blood and Transplant said: “Living donation is highly successful, and hundreds of people have had their lives saved and transformed, thanks to the generosity of these donors.
"Non-directed altruistic donors really are the game changers in the kidney sharing scheme. Living donation has been a major success story for the UK, with one in three patients receiving a kidney transplant from a living donor."
To find out more visit www.giveakidney.org #ShareYourSpare