(EDGE) Transgender triathlete Chris Mosier is the star of a new ad from Nike's "Unlimited" campaign, which features athletes who push their own limits.

According to a press release from the company, Mosier "began competing in the duathlon and triathlon in 2009 after he completed his first marathon, because he needed a greater challenge."

"For me, triathlon is a true challenge because it is three different disciplines in one sport," Mosier said. "Triathlon is [also] a challenge for me because swimming is my weakest sport, and it's the biggest mental challenge."

Mosier was four-years-old when he became aware that his gender identity did not meet his biological sex. Mosier did not feel as his authentic self when playing against females.

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"Everything that I've done in the last five, six years since I started to transition, has been with [a] 'Just Do It' mindset," he said. "I didn't know if I would be competitive against men; I just did it. Every success that I've had since then has shown me that anything is really possible. By not stopping myself, not limiting myself and just really going for it, I've learned a lot about myself and also had the opportunity to further the conversation on trans inclusion in sports."

In 2015, Mosier became the first trans athlete to earn a spot on a U.S. national team, thus challenging the international transgender competition policy. Because of Mosier, new guidelines were set for trans athletes.

Watch Nike's ad below and read more about Mosier by clicking here.