Fast facts: Cameron Clayton

Age: 24

Education: University of Colorado-Boulder

Studied: Biology and Spanish

Career goals: Become a professional distance runner

Hometown: Superior, Colo.

While running the North Face Endurance Challenge 50-mile race in San Francisco earlier this month, Cameron Clayton said at least one part of his body hurt at all times during the race.

But he said his pain made finishing his second ultramarathon in third place that much more satisfying.

Clayton, a 2012 University of Colorado-Boulder graduate and alumni of the CU cross country and track and field teams, beat out more than 240 men for the bronze finish. Two professional runners from the Salomon running team, Miguel Heras and Franois d'Haene, finished ahead of Clayton.

A few days before the race, officials announced a course change due to a weather system slated to move in that weekend. The new course became a roughly 25-mile figure-eight shape that runners completed twice.

Rain poured for most of the race, Clayton said, and temperatures hung in the 50s. Because competitors traipsed through the course twice, it quickly became slippery with mud.

"Something like 4 inches of rain fell that day, which compared to Boulder, is a hell of a lot," Clayton said. "The terrain deteriorated pretty badly."

At times, Clayton said he ran on all fours while trying to get back onto his feet.

"I can't understand how they could even see, much less run," said his father, Brad Clayton, who cheered on his son at the race.

For the first 10 miles, Clayton said he chatted with other runners and worried about eating and drinking enough to stay energized.

But then, it became a mental game as he tried to run through the pain.

"For 40 miles, I'm in constant pain," Clayton said, recounting how he felt for the majority of the race. "Something is hurting. My calves were screaming -- I thought I was going to tear a calf. So I was just trying to maintain, just holding it together. And that's what I do. I don't think about anything else too much."

At CU, Clayton ran the steeplechase during track season and competed in cross country. Before his first ultramarathon earlier this fall, his longest race distance was 10k.

Clayton studied molecular cellular developmental biology and Spanish at CU, but said he's aiming to run full time. He's currently looking for sponsors or a team, and a part-time job to help pay the bills.

"There's adventure in it," he said. "I will run as long as I can. There's a lot of great aspects that help you grow when you go and do challenging things."

--Follow Sarah Kuta on Twitter: @SarahKuta.