Team USA's Chris Mosier Is First Transgender Athlete Featured in Nike Ad

Duathlon competitor Chris Mosier keeps making history. In June, as the first out transgender person to be be named to Team USA, he represented the U.S. at the Duathlon World Championships in Spain. Then Monday night, in a new ad titled "Ultimate Courage," Mosier broke new ground again as the first transgender athlete in a Nike ad.

The commercial features Mosier training for his grueling endurance sport, which involves biking and running. He addresses all of the challenges he's overcome to reach this incredible achievement.

Mosier shared the commerical online in wonder. "When I was a kid, I dreamed I would be in a Nike commercial," he wrote on Twitter. "Your limits are only defined by you."

Mosier will not be in the Olympics, as the duathlon is not an event in the Summer Games in Rio De Janeiro. He has noted that there are no out trans athletes in the games -- there are reportedly a couple who have not come out publicly -- but this year's Olympics are the most open for trans athletes ever. New rules issued by the International Olympic Committee this year removed all surgical requirements for trans people to compete in events concordant with their gender identity.

In an interview with Rolling Stone earlier this month, Mosier talked about why he worked to become an openly trans world-class athlete.

"When I think back to growing up as an athlete, every positive thing that I learned about goals, dedication, leadership, and values I learned from playing sports -- this was an area of my life where I felt the best about myself," he said in the interview. "That shouldn't change because a pronoun has changed. I took this on because I think all athletes and all people should have the opportunity to play sports and have a place where they can feel their best about themselves."

EDITOR'S NOTE: An earlier version of this story identified Mosier as a competitor in the Olympics. However, his sport is not part of this year's Summer Games.