For the first time in four years The Ironman 70.3 World Championship is back in the United States and it is being held in Downtown Chattanooga.

Thousands of athletes from around the world are participating this weekend, including one woman who is turning tragedy into triumph.

Jennifer Knowles qualified for the world championship at 62 years old, after competing in her first ever Ironman competition. She has been training over a year for this weekend both physically and mentally. 

Jennifer Knowles has competed in dozens of triathlons and marathons. But one thing, never gets easier. “At the swim I am not competing, at the bike and the run I feel like I am competing,” said Jennifer Knowles.

Jennifer's son drowned when he was three years-old. She has spent the last 22-years avoiding the water. “That is part of my panic, when I look down and see that dark water. Sometimes, I start feeling that sacredness.”

But Jennifer is ready to go the distance, and beat her fear. “One of the things about losing a child is, you don't get over it, you learn how to live with it. This is part of my learning to live with it and this ongoing challenge trying to be the person you can be despite what happened in your life.”

It's been a long journey for Jennifer, which has included months of training and years of work to overcome her fears. She knows, during each leg of the race, her son will be there with her.

“I have my little angel necklace that I wear. I wear it during the races and I just say, help me out Chrisy. I am having a hard time. That helps me get through the races, get me through the swim anyways.”

About 4,500 athletes from 90 countries will compete this weekend. Jennifer's story is a great example of how each of them has a story and a motivator in this race.

Jennifer is from Toronto. This is her first trip to Chattanooga.

She will compete in the women's race on Saturday. Men compete on Sunday.