Claressa Shields is a force to be reckoned with.
At 26 years old, Shields is a powerhouse inside the boxing ring as the first undisputed champion in two different weight classes during the four-belt era.
Now ready for a new challenge, she's making her mark in mixed martial arts.
The two-time Olympic gold medalist has signed with the Professional Fighters League, a change in her career that she said was borne out of her experience during the past year of the coronavirus pandemic.
"Going through the pandemic, it was a depressing time," Shields told Michael Strahan in an interview that aired Tuesday on "Good Morning America." "I wasn't in the ring. I had gained a whole bunch of weight and I'm like, 'I've accomplished everything in boxing.'"
"In my mind, I'm just like, 'You know what? I think it's time to try MMA,'" she said.
Shields first stepped into the boxing ring at the age of 11, a childhood sport that changed her life.
“The best decision that my dad ever made was to let me box," she explained, adding that she had a difficult childhood.
"Growing up, I didn’t have a whole bunch of food. I didn’t have clothes and I didn’t have shoes,” said Shields, a native of Flint, Michigan. "I didn’t have a bed until I was 17 years old. It just kind of taught me that anything I want I have to do for myself."
MORE: Meet the female boxer who was named a 'force of change' by Duchess MeghanAs a boxer, Shields has put a spotlight on the sexism that she says exists in the traditionally male-dominated sport. She has been vocal about wanting to grow the sport of women's boxing and wanting women to have equal pay and equal opportunity, saying, "There are a lot more changes that need to be done."
"It is just an unfair playing field," said Shields. "The pay discrepancy, it's mind-boggling to me. There's not a boxer -- male or female -- who have accomplished what I've accomplished."
This year, Shields put together a history-making, all-female boxing event and brought it to pay-per-view after tiring of waiting for television networks to air women's boxing matches.
Now, as she adds mixed martial arts to her resume, she hopes to continue setting an example for all women.
MORE: NCAA under fire again for inequities in women's athletics after star's viral videoShields will make her PFL MMA debut on June 10.
"Be the woman who you want to be," she said of her advice to other women. "Sometimes they put us in this box and they say this is what a woman is, 'Skinny, petite, straight hair,' and they just put you in this box and it's so shallow."
"I think that people are so used to women just being told what to do and not doing what they want to do that it kind of makes them uncomfortable and makes them feel intimidated," Shields said of women like herself speaking out. "That's my advice to the women, do you, boo."