The 28-year-old who saved a stranger's life — and sparked a chain that saved four more

Warmth: Recording Small Acts of Kindness

Living kidney donor Kim Se-young, 48, speaks in a phone interview about the "life-sharing relay" that grew from a single act of generosity — and the ultramarathon journey that followed

Kim Se-young at the time of his kidney donation in 2007. [Provided by reader]

"When I finish 100 ultramarathons, I want to make a commemorative towel. I'll write three lines on it to sum up my life: 'Kidney donation in my 20s. 100 full marathons in my 30s. 100 ultramarathons in my 40s.'"

In his 20s, Kim Se-young gave one of his kidneys to a complete stranger. In his 30s, he ran the 42.195-kilometer marathon distance 100 times. Now 48, the living kidney donor is chasing his next milestone: completing 100 ultramarathons.

Kim has finished 79 ultramarathons to date. Six times he has completed a 308-kilometer trans-Korean Peninsula race that begins on the West Sea, crosses Daegwallyeong Pass and ends at Gyeongpodae on the East Sea. Blisters on his soles and a body worn out from the effort have never been enough to make him stop.

There is a reason Kim runs the way he does. After donating a kidney to a stranger 19 years ago, people around him worried — asking whether he was all right with only one kidney, or whether his health would deteriorate. Rather than answer in words, Kim wanted to answer with his body: that a person can live a full, healthy life after giving away an organ.

A mining-town boy's dream of giving life

Kim grew up in the coal-mining town of Taebaek in Gangwon Province, an ordinary boy who ran through mountain valleys catching crayfish and frogs. When the mining industry declined, his family followed his father to Incheon, and as an adult Kim settled into a routine life working at a manufacturing company.

Then came the first turning point: an American forensic-science documentary he happened to watch. Seeing how bodies donated after death were used in medical research and criminal investigations, he realized that death did not have to be simply the end of a person. A body left behind, he thought, could become "life's final gift" — something that helps someone else.

Kim promptly pledged to donate his body to Inha University Hospital. Wanting to be in a state he would not be ashamed of when his body was eventually passed on to medical students, he also quit smoking.

As time passed, another thought began to take shape. Was there something he could do now, while he was still young and healthy, rather than waiting until after death?

The autobiography of independence fighter Kim Gu, which he read avidly, also moved him.

"I knew I couldn't be the kind of person who lays down their life for a cause, but I wanted to be someone who could help others. Donating my body is something that happens after I grow old and die. I wanted to do something meaningful while I was young and at my healthiest."

In 2007, at the age of 28, Kim applied to donate a kidney while still alive.

Making the decision did not mean he could go straight to the operating table. Because he was giving an organ to a complete stranger with nothing in return, counseling sessions lasting several months were required to confirm that his intention was genuine and that no financial motive was involved. He was told he could change his mind right up until the moment of surgery.

Recalling that time, Kim said his parents initially worried and tried to dissuade him, but he persuaded them by asking: "Couldn't this be a desperate wait for someone who can barely count on tomorrow?" He added, "Donating a kidney was the most meaningful thing I could do when I was young and healthy."

The butterfly effect of organ donation, discovered in a newspaper

Kim never knew who received his kidney. He had one wish: that it go to whoever was waiting most desperately for a transplant.

The answer came from an unexpected place.

One day while recovering in the hospital after surgery, his doctor handed him a newspaper. It carried the story of a father in Busan who had received Kim's kidney. Donor-recipient confidentiality rules had kept Kim from knowing where his kidney had gone, so it was the first time he learned its fate.

The wife of the man who received Kim's kidney went on to donate one of her own kidneys to another patient, and that act of giving passed on to the next person in turn. The single kidney that 28-year-old Kim had given to a stranger rippled outward like a butterfly effect, giving four people a new lease on life.

People ask me, "Don't you really regret it?" or "What did you get out of it?" But there is always a sense of pride inside me. The feeling that "I saved someone's life in my 20s" — I think that's what has let me live positively for the rest of my life.

Living kidney donor Kim Se-young, 48, smiles after completing the 20th Suncheonman Ultramarathon on Saturday. [Provided by reader]

The worry and prejudice Kim encountered after his donation played a large part in turning him into a "life-sharing runner." He wanted to answer with his own healthy life the widespread concern that donating a kidney would ruin one's health.

In 2008, the year after his surgery, he happened to receive a postcard advertising the Incheon International Marathon. After five or six months of training, he completed his first full 42.195-kilometer course.

What he thought would be a one-time experience became the second turning point of his life. He achieved 100 full-marathon completions in 2014, and on Saturday he crossed the finish line of the 20th Suncheonman Ultramarathon — his 79th ultramarathon overall.

"If I hadn't donated, I probably would have kept smoking and taken my health for granted," Kim said. "Going forward, I want to keep taking good care of myself so I can be a dependable father for a long time to my daughter and son, who are still in elementary school."

The 13th Seoul Organ Donation Day ceremony is held Wednesday in front of the education building of the Seoul Museum of Craft Art in Jongno-gu, Seoul. [Provided by the Korea Organ Donation Association]

According to the organ donation and transplant statistics yearbook published by the National Institute of Organ, Tissue and Blood Management under the Ministry of Health and Welfare, there were 46,896 people on the national organ transplant waiting list as of March 31. Of those, 37,023 — about 79 percent — were waiting for a kidney. The average wait for a kidney transplant stands at 2,180 days, meaning patients wait nearly six years on average.

Cumulative registrations for organ donation have reached about 2.03 million, but the number of new registrants has barely grown. From 88,865 in 2021, the figure fell to 69,439 in 2022, then moved to 83,362 in 2023, 70,563 in 2024 and 72,823 last year — stuck in a range of roughly 70,000 to 80,000 for five consecutive years.

Calls have consistently grown for stronger recognition of donors and their bereaved families as a way to encourage more people to register.

Kim Dong-yeop, standing director of the Korea Organ Donation Association, said the country must strengthen "practical and sustained support systems" — including scholarships for donors' children, psychological counseling and grief support for bereaved families, peer networks and self-help groups among families, and memorial events honoring donors. "When families come to trust that the state and society will remember and respect donors and their loved ones long after the donation, the anxiety and burden that families feel about organ donation will also ease," he said.

kido@heraldcorp.com