Nearly 30 years ago, before the Human Organ Transplant Act made organ donation the default in the event of a person's death, Mr Lim Kok Seng signed up to be an organ donor.
Twenty years later, he started volunteering for clinical drug trials to help advance medical science.
And in January last year, the 54-year-old security concierge decided to take things a step further, by coming forward to donate part of his liver to whoever on the national waiting list needed it most.
That turned out to be 16-year-old Lim Si Jia, whose own liver was unable to break down a compound called glycogen properly.
Following 10-hour surgery at the National University Hospital on March 24 this year, Mr Lim became the first non-directed liver donor in Singapore's 26 years of carrying out liver transplants.
Left untreated, Si Jia's condition could lead to cancerous tumours forming on her liver and prove fatal in the long run.
Professor Krishnakumar Madhavan, co-director of the National University Centre for Organ Transplantation, said the majority of living organ donations worldwide are directed - that is, the donor has a specific recipient in mind. Said Prof Madhavan: "This is the first time in our experience with somebody who steps up and says, 'I want to donate; it doesn't matter to whom.'"
Mr Lim, who simply wanted to be able to help someone, decided not to wait until after his death to donate his liver because he was not sure whether it would still be in good working order by then.
"When you are above 60, you know, complications do come in all forms," he said. "Even if I made the pledge, my liver might not be good (enough) to help any more."
He also wanted to make the donation before he turns 55, as doctors generally recommend that people who want to donate their organs do so before this age.
Typically, potential donors go through a lengthy counselling process over months to make sure they are aware of the risks and still want to go ahead. They are given the option to back out at any time before the surgery. Both sides do not know who the other person is until after the operation - and only if both agree to disclosing their identities - so as to avoid feelings of obligation.
Mr Lim met Si Jia, who now has 60 per cent of his liver, for the first time about a month ago. The rest of his liver will regenerate within three months, doctors said.
Said Mr Lim: "I had only one request, which was that (the liver) be given to a younger (recipient), so that they have much more life ahead of them."