Do you have a weight-loss success story to share? Tell us how you did it and you could be featured on CNN.com.
(CNN) -- Dan Hyatt's wife, Shelley, had been worried for a while by the time he hit 337 pounds.
Her husband had a short fuse and a bad attitude because he hated the way he looked and felt. He was on multiple medications for high blood pressure and used a CPAP machine at night to treat his sleep apnea. She tried to dance around the problem, but she was afraid of becoming a widow.
"A couple times I said something like, 'How much life insurance do you have?' " she said. "I was afraid if I said, 'I'm afraid you're going to die,' that would make it come true."
On January 13, 2012, Hyatt crawled to the top of a tower at the plastics plant where he worked, doubled over and struggled to catch his breath. That was when it finally hit him -- if he didn't lose weight, he might not live to see his three daughters graduate college, get married or have children of their own.
Heavy all his life from poor eating habits and little exercise, Hyatt had lost weight before only to gain it all back. So this time, he didn't set a weight loss goal.
He gave himself a bigger challenge: Compete in an Ironman triathlon in five years or less. Arguably the world's most grueling endurance race, the Ironman consists of a 2.4-mile swim, a 112-mile bicycle ride and a marathon 26.2-mile run with no break.
"I can't explain how my logic works, but I just decided, if I try to run the Ironman, even if I don't get there, I'm going to lose the weight and I'm going to get fit," said the 44-year-old from Ottawa, Illinois.
Eight months later, Hyatt had completed his first triathlon, run his first marathon and lost nearly 100 pounds. To date, he has lost 135 pounds and 12 inches off his waist by working out 12 to 14 hours per week -- swimming, running, cycling and doing yoga -- and sticking with a fairly rigid diet.