It is a grueling test of endurance and a gauge of how far the mind can push the body, but Ironman competitions do more than test one's stamina. These rigorous races also help those in need.

Big Brothers/Big Sisters of Colorado is one of hundreds of nonprofits that benefit from Ironman competitions each year. In fact, Denver-based Janus Capitol Group encourages athletes to use Ironman events as a way to raise money for nonprofits.

David Spilsted has competed in three Ironman races. He's a money market trader at Janus.

"I've always wanted to do some sort of work to put something back into the community and this was a great way to do it," said Spilsted.

"David in the last two years has raised about $25,000 for Big Brothers/Big Sisters," said Chris Craig, with the Big Brothers/Big Sisters organization.

"You never say, 'I can't do it.' You just find a way to do it," Spilsted said.

He also contributes his time and visits with kids involved in Big Brothers/Big Sisters programs to talk about overcoming life's obstacles.

"I just want the kids to know that really anything can be achieved if they put their minds to it," he said.

"And he inspires the kids to know that it is hard. Some days you wonder if you can do it, but you just keep going and when you cross the finish line, it's worth it. And that's the biggest reward," Craig said.

Janus Capital Group helped raise more than $4.5 million for hundreds of nonprofit groups nationwide.