How Rumer Willis Found a 'Different Confidence' in the Face of Cyberbullies

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Rumer Willis refuses to let her cyber bullies get her down.

The 26-year-old daughter of Bruce Willis and Demi Moore penned an essay for Glamour magazine in which she opened up about the bullying she faced growing up in the spotlight. Now she's talking to ET about cyberbullying and how young people can overcome it.

WATCH: Rumer Willis Gets Candid About Constantly Being Bullied for Her Looks

"When I was a kid you didn't have Twitter or Instagram where as soon as you walk out of a building a photo of you is up within two minutes or a million people are commenting and saying nasty things," Willis told ET. "I found a different confidence because I realized that you can't base your self-worth on the opinions of others."

In her essay, Willis revealed that she kept her insecurities about her looks hidden from her famous parents "because it was too painful," but a key piece of advice from her mother gave her piece of mind.

"I remember my mom telling me, 'There's always going to be someone who's a better singer. There's always going to be someone more fit. There's always someone who's going to be, in your mind, better than you - who you're comparing yourself to. But you can't do that, because you will live such an unhappy life,'" Willis wrote.

And she's putting her mom's advice to good use!

Willis shimmied her way to a mirror ball trophy on the last season of Dancing With the Stars and will jazz up the Broadway stage later this summer.

NEWS: Rumer Willis to Make Her Broadway Debut in 'Chicago'

Starting Aug. 18, she'll be taking on the iconic role of Roxie Hart in Chicago, a character Renee Zellweger, Brooke Shields, Brandy and Christie Brinkley have previously played.

"Obviously so many different women come into this role," Willis said of her new gig. "I feel like they do a really incredible job of making sure that each woman that comes in is really able to make the character her own. I sat down and just to being able to put on the wig and have the whole character come together has been incredible."