Tyler Stewart

Tyler Stewart, who won Ironman Coeur d'Alene in 2010, has made the move from professional triathlete to ultra-runner.

Joanna Zeiger and Tyler Stewart proved that they have single-sport prowess and qualified for the Olympic marathon trials in Houston.

Even the pros—Chrissie Wellington included—had to start somewhere. We polled some of the pros to get them to share some of the lessons they’ve learned (often the hard way). Learn from their mistakes so you don’t make the same ones.