Former Olympic gold medalist McKayla Maroney is all grown-up now and ready to take on those internet trolls!

In an exclusive interview with ET’s Lauren Zima at The Dub Room Studio in Los Angeles, Maroney, who catapulted to fame after competing with the "Fierce Five" at the 2012 Summer Olympics in London, sets the record straight about those rumored lip injections.

WATCH: Kylie Jenner Finally Reveals the Truth About Her 'Temporary Lip Fillers' 

"I'll be very honest, I have not done anything to my face," admitted Maroney. "But it's like these are rumors that are going to come up for the rest of my life and I can't keep responding to them. People are always going to have opinions and it's just better to move on and keep doing you."

Maroney, who is now focusing on a singing career, says her new pout is simply just a makeup trick.

"Basically, I'm wearing lip liner," she said, also adding that she no longer pays attention to haters. "I don't read comments. People on social media are definitely mean and they'll say some stuff that will catch you off-guard. The best thing is to just know that you are good enough … and you really don't need to fit in. Fitting in is overrated. It's so amazing to be different and special and the most important thing is to feel good about who you are."

RELATED: McKayla Maroney Opens Up About Her 'Changing' Appearance Amid 

Sadly, after a series of injuries, Maroney will not compete at the upcoming Summer Olympics in Rio de Janeiro, Brazil.

"It was a little more than a year ago. I had four different surgeries," the 20-year-old explained. "I had a concussion, a fractured shin and a fractured foot. I wasn't OK. I couldn't get out of bed, I was passing out all the time and was in the hospital. Every time I would go back into the gym I would hurt something or I would get really sick."

Eventually, Maroney came to the realization that she had to retire from gymnastics.

"Gosh that was a heartbreaking moment for me," she continued. "I [had] several small moments [where I thought,] 'Why isn't this coming together?' As hard as it was to accept, I did. I went through a year of real bad depression. [It] was horrible obviously, nobody wants to go through that."

She's now focusing on her second passion, music. Her new single, "Ghost," will be released on September 8.

"Music for me is something that's healing and [makes me] feel so happy," she explained. "I think people [will] see that and they're going to hear that in my music."

"I've loved music since I was like 8 years old. I would write songs," she added. "It was really hard to accept that gymnastics [had] come to an end ... that was my identity you know."

WATCH: Kylie Jenner Admits Her Lips Were 'Too Big' At One Point 

Another celebrity who's received a slew of hateful comments for her voluptuous lips is Kylie Jenner. Earlier this month, the 18-year-old reality star admitted that she regretted making her lips "a little too big at one point.” Hear more in the video below.

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