At 4 p.m. on the day before last month’s Boston Marathon, Kim O’Callaghan, 47, of Vineyard Haven, could have been expected to have her mind on preparing for the next day’s race—which would be her 14th go up Heartbreak Hill. (She ran this year’s race in 4 hours, 51 minutes and 40 seconds.)

Instead, she was checking a just-published list of 100 names, and thinking of October.

“If you look at the names,” Ms. O’Callaghan said in a Gazette interview, “forty are from the States, and there are only nine women.”

“And me!” she continued, with a smile that took over her entire face.“A florist on Martha’s Vineyard!”

Ms. O’Callaghan, owner of Morrice Florist, wasn’t looking at the marathon list. Rather, she was scrolling through a list of triathletes, future competitors in the 35th Ironman World Championships in Kona, Hawaii. As one of those selected for the October field, she joins an elite group of triathletes from across the globe.

An Ironman triathlon consists of a 2.4 mile swim and a 112 mile bike ride, capped off with a full marathon (26.2 miles). The race was first held in 1978 in Kona; since then, other courses have been established around the world (most in the United States and Canada). Kona, however, remains the home of the world championships. Unlike other Ironman courses where participating is as simple as signing up, Kona requires a qualifying time or selection through a lottery system. This year, for the first time, Ironman opened the field to one hundred Legacy Athletes--those who had previously competed in at least 12 Ironman races, and had already signed up to participate in another in 2012.

“I don’t know why I got picked over someone else [another legacy athlete],” Ms. O’Callaghan said. “You had to write a little story [to apply]...I kept saying ‘I’m from the little Island of Martha’s Vineyard; I want to go to the Big Island. Maybe that helped.”

But with 14 Ironman races (that’s 33.6 swim miles, just over 1,500 bike miles, and 366.2 running miles, to say nothing of the training miles logged) already under her belt, and a 15th planned for this summer, she might not have needed the extra push.

Ms. O’Callaghan runs and bikes in the morning with training partner Bill Brown, goes to work at the flower shop — carrying on the family business her grandfather started in 1940 — and is home at day’s end to take care of five-year-old son Hunter (older children Liam and Gillian are both in college).

“When I was 18,” she said, “I went on Outward Bound...it changed my life. I think that’s where all this is rooted, because the two things they put in my head were you gotta live life, and that we sell ourselves short.”

Still, she didn’t take up running until she was in her late 20s and, as she describes it, “a two-pack-a-day smoker; isn’t that funny?” This led her to marathons (about 60 total) and the 14 Ironman competitions.

In honor of the impact Outward Bound had on her life, she is raising money through the Ironman Foundation to provide financial assistance for Island teens to have the same experience.

Ms. O’Callaghan’s first Ironman was in Panama City, Fla., in 2000.

“I smiled the whole way; it was so bizarre,” she remembered. “And everything hurt, but I was like ‘Yeah, this is the best.’ I couldn’t believe I could do it.”

Both of her parents flew down to watch the race, which would be the only one her father, John Novak, was able to see. Mr. Novak died of cancer the next year; Ms. O’Callaghan wears his dog tag from the Korean War in all of her races. After learning she made the Kona field, she went to the cemetery to thank him.

Continuing the family appearances tradition, Gillian and Liam plan to fly out to Hawaii. “Some people don’t get how big it is — my kids were like ‘I don’t care; I don’t care if I have to skip the whole semester, Mom—I’ll be there.” They were also at the finish line when Ms. O’Callaghan completed her best-ever Ironman in Cozumel, Mexico in 2010 with a time of 11 hours, 48 minutes.

As with most triathletes, the swim portion is her weak point. “Two thousand people jump in the water at once, and it’s really scary,” she said. “You get hit, and punched, and poked, and you come out of the water, and you’re [thinking] ‘I’m alive!’”

But, she added, falling behind in the swimming leg has its benefits—like easily finding your bike for the next leg.

“Cycling’s my strongest part, so all day on the whole bike ride I pass people,” she said. “You just feel like you’re awesome.”

She’s not much interested in completion times. The idea is not to collapse halfway through from overexertion but to finish in a time that makes sense.

“I want to do the best for me,” she said.

“The hardest part, the absolute hardest part, is signing up,” Ms. O’Callaghan said. “Once you sign up, you’ll do it...you know, you just keep going forward and you’ll get there.”

Kim O’Callaghan will compete in the 35th Ironman World Championship in Kona, Hawaii on October 13, 2012. Through the Ironman Foundation, a 501(c)(3) nonprofit, she is raising money to send Island teens on Outward Bound trips. You can donate to this cause via http://ironman.kintera.org/worldchampionship2012/mvkim13