There are thousands of athletes competing in the 2016 Rio Olympics, and all of them have a story about their journey, but one that has really captivated us is that of boxer Claressa “T-Rex” Shields.

In 2012, Claressa became the first American woman to earn an Olympic gold medal in boxing, a monumental achievement for anyone, but especially for a then 17-year-old living in poverty in Flint, Michigan.

Claressa comes from a tough background. She grew up bouncing between homes while her father was incarcerated, and her mother struggled with addiction. But instead of having her life experiences break her spirit, they motivated her to be stronger.

“They said boxing was a man’s sport. It wasn’t the right reason to tell me not to box.”

At 11 years old, when Claressa’s dad was released from prison, he told her stories about Muhammad Ali and his daughter Laila Ali, and introduced her to the boxing ring. Early on, it was obvious that she had the talent to take it all the way. Her coach Jason Crutchifield and his family took her in and kept her focused; she has been winning ever since. Now with a record of 69-1, she is ranked number one in the world heading into her second Olympic competition.

The new documentary film, T-Rex: Her Fight for Gold, from PBS Independent Lens, traces Claressa’s rise, and the subsequent challenges and disappointments she continues to face in spite of her incredible success. In the above clip, Coach Jason reminisces about how Claressa first began as a boxer. Watch the film in its entirety here.