Hospital pharmacy manager Peter Mui walks around the Chicago suburb of Glenview wearing a watch engraved with the words "the gift of time for time given".
It was a present from Singaporean priest Luke Fong - a complete stranger 15,000km away whose life he saved by donating his stem cells.
The 50-year-old Catholic priest, a fitness enthusiast, was diagnosed with a potentially fatal strain of leukaemia in 2013. Six months after his diagnosis, the Bone Marrow Donor Programme, which is linked to an international registry, found a match in Mr Mui.
Dropping everything, Mr Mui underwent a relatively painless process. There are two ways to extract stem cells: a bone marrow harvest, and peripheral blood stem cell harvest, which is more common.
Mr Mui underwent the second procedure, which included five injections over several days and being hooked up to a machine for five hours to extract his stem cells, in a process similar to blood donation. He experienced aches and fatigue and had to rest for a few days.
"I didn't know who the recipient was but I thought about his family and the people who love him," Mr Mui, now 48, told The Sunday Times by telephone. "How can anyone say no to saving a life?"
Father Luke, who is still recovering from the July 2013 transplant, flew to Chicago two weeks ago to say thank you to Mr Mui. Their meeting was reported by American media, including the Chicago Tribune and NBC's evening news.
Father Luke, who got home last Wednesday, said Mr Mui's selfless act was "unfathomable". He was was flooded with a "gamut of emotions" when he first saw him at O'Hare International Airport.
"He didn't owe me anything yet he went out of his way to save someone he didn't know. I flew over to thank a stranger who has now become a friend and a blood brother.
"I hope Peter wears the watch proudly and that his children can carry on their father's legacy of giving hope to others."
The assistant parish priest from the Church of the Immaculate Heart of Mary near Kovan had been on a break from graduate theology studies in Washington, DC when fever and fatigue overcame him while on a trip to New York.
Thinking he had iron deficiency, American doctors prescribed him iron tablets. "I was very sick for a month and could hardly walk. I was losing a lot of weight and missing classes," said Father Luke. He flew back to Singapore for medical treatment and was given the bad news. He underwent chemotherapy and was told he needed a transplant.
Bone Marrow Donor Programme data shows that every day, about six Singaporeans are diagnosed with a blood-related disease.
Father Luke's 5,000-strong parish was shocked to hear the news, said Mr Michael Vong, 52, the co-chairman of the church's pastoral council: "All of us were devastated. We are so used to seeing him fit and strong. He used to wake up, pray and then do 10km runs."
Rallying behind him, hundreds from the Catholic community had their DNAs registered as part of the Bone Marrow Donor Programme's database.
On a few occasions, Catholic Archbishop William Goh visited Father Luke in hospital and met his parents to pray with them. Father Luke took to his blog to share his journey with worshippers and others stricken by chronic illnesses.
Last month, doctors gave him the green light to travel to the United States. He stayed with Mr Mui, his wife and two children aged nine and 12, for about a week.
He cooked breakfast for the family and met Mr Mui's parents. They also visited the room where Mr Mui's stem cells were extracted.
Mr Muilost a childhood friend to leukaemia in 1984, when they were 16. Jon Grebin was diagnosed at the end of the school year and died in three months. "I didn't even have the time to say goodbye to him properly," he said. "Leukaemia is so hard on the body and the spirit. It is a crushing way to die."
On June 20, 2001, Mr Mui had his cheek swabbed for his DNA at achurch drive to do his "small part" for someone in need.
It was the same day Father Luke, who used to work in the hotel industry, was ordained in Singapore.
Father Luke is still being treated at Singapore General Hospital where his blood cell count is taken every six weeks. He suffers aches in his joints and water retention and can barely run 500m.
But the disease has given him new direction. He is now an advocate for the Bone Marrow Donor Programme. He speaks in schools and organisations, encouraging people to join the local bone marrow register. As of last year, it had 48,000 potential donors, up from 38,000 in 2013. The aim is to double the pool to 100,000 by the end of 2018. The programme's chief executive Jane Prior said: "We're battling to get through to people that a bone marrow or a blood stem cell donation is a simple and straightforward procedure with no long-term side effects."
Mr Mui did not expect the recipient of his stem cells to be a priest. "I wear the watch every day, as a reminder of Father Luke. I'm happy to see he's doing better and now has more time to bless others."
Sign up to be a donor here at http://bmdp.org/sign-up-button/