Rain or shine, Peter O’Neill always competes in the triathlon (铁人三项运动) of his town. The 72-year-old has competed in every triathlon in the event’s 40-year history. He was part of the group that came up with the idea in the 1980s.

“I used to jog around town,” Mr. O’Neill said. “I came into contact with an Olympian, David Power, and Dave had a hotel up here. A few of us got together and we discussed it and got it going in October, 1983.”

The then 31-year-old suggested one of the group should compete. “Everyone else could either ride a bike or run, but I was the only one who could swim,” he laughed. “But I was happy to give it a go.”

In the beginning, more than 220 athletes took part in the event, including 79 individual competitors and 48 teams. These days it’s a five-day festival—which includes 11 events in all—with more than 13,000 competitors.

Rebecca van Pooss, head of operations for the triathlon there, said the event Mr. O’Neill helped to start was now an international event. “It is the world’s largest Olympic-distance triathlon,” she said. “That’s something we’re very proud of.”

“Mr. O’ Neill’s efforts were inspiring. There are a couple of other athletes who have done 38, 39,” she said. “But Peter, he is the legend (传奇)—it’s pretty amazing to have someone who’s done all 40 of our races.”

Mr. O’Neill trains year-round for the event, and enjoys the social side just as much as the physical benefits. “I’ve made so many friends… friends that I ride with and friends I swim with—it’s been wonderful,” he said. “When you’re in your 70s like I am, you’re quite happy to just do it because you know it beats the alternative (替代品), which is sitting around doing nothing.”