It's one of the longest races organized by the World Triathalon Corporation.
Thousands of people take on the Ironman challenge every year. One Penfield woman is representing Western New York in Ironman's international competition next month.
"Weirdly I do a lot of math in my head, how much further I have to go. There's a lot of just trying to not think," said Jennie Hansen.
That's how Hansen gets through her training.
"I was training about twelve to fourteen hours a week. For the full Ironman it's anywhere from twenty to twenty-eight," said Hansen.
Hansen started running in triatholons four years ago. After competing in several Ironmans, she took on the Lake Placid competition again in July. For those who don't know, Ironman goes like this: swim for 2.4 miles, bike 112 miles and then run for 26.2 miles.
Hansen said it usually takes her around 9.5 hours to complete.
For most participants, the achievement comes in just being able to finish the race, but two months ago, Jennie achieved much more than that when she became the 2013 Lake Placid Female Champion.
"Just running for my life until the end, once I hit the stadium I kind of knew I had it. It was definitely a big relief and I definitely left myself out there on that course," she said.
Hansen ran track and cross country both in high school and college but never thought she would be this successful.
"I was never the star, just sort of the consistent one," Hansen said.
In three weeks, Hansen will compete against the best women in the world in the superbowl of Ironman racing in Kona, Hawaii.
"It's the best women in the world and I'm just gonna go out there and give it a go and hopefully not come in last," Hansen said.
Until then, her husband, who also competes in Ironman, will train with her.
"It's something that I will be able to have, I was an Ironman Champion but hopefully it's the start of more to come," she said.