In an emotional interview on NBC's "Today" show on Thursday, Biles said she's still struggling with the "twisties" as she performs on her Gold Over America Tour. The twisties is a mental block where competitors can lose track of where they are while in midair.
"I don't twist (on tour). I do double lay half-outs, which is my signature move on the floor. That's never affected me. But everything else weighs so heavy, and I watch the girls do it, and it's not the same," said Biles, arguably the greatest gymnast of all time.
"But the twisting, once I got back, will come back. But I'm still scared to do gymnastics," she added.
Biles, 24, who has won seven Olympic medals, including four golds, battled mental health issues and the unexpected loss of a family member during the Summer Games.
'I'm happy that I can be a leader for the survivors'
Last month, Biles testified before the Senate Judiciary Committee regarding the FBI's handling of sexual abuse claims against former USA Gymnastics team doctor Larry Nassar.
Biles, alongside McKayla Maroney, Maggie Nichols and Aly Raisman -- all of whom were abused by him -- focused on how the FBI botched its investigation and the intimidation that came from the sport's governing bodies.
"For so many years to go through everything that I've gone through, put on a front, I'm proud of myself, and I'm happy that I can be a leader for the survivors and bring courage to everybody speaking up, so I'm happy to be a voice for them," Biles said on Today.
At the Olympics, Biles withdrew during the team final and then withdrew ahead of the all-around final and individual events of vault, uneven bars and floor exercise. She did compete in the balance beam final, winning bronze.
"To do something that I've done forever and just not be able to do it because of everything I've gone through is really crazy, because I love this sport so much. It's hard, I'm sorry. And I don't think people understand the magnitude of what I go through," Biles said, her voice breaking up.
Biles said she has many techniques to help with her mental wellness, including using the mental health app Cerebral. She is now the chief impact officer with the company.
"Getting the mental health therapy that I need has been really relieving for me, especially being on the road and on tour. I'm happy to have such a great app to help out with that," she said.
Biles said she also likes taking walks outside and indulges in a little retail therapy.
CNN's Jill Martin and Jack Bantock contributed to this report