Shame and vulnerability researcher Dr. Bren Brown says we all have a choice in life whether to put our true selves out there or hide behind our fears. While many people are afraid to be vulnerable, Brown explains in this clip from "Oprah's Lifeclass" why the alternative is far worse.

In the video, Brown starts by reciting a quote from President Theodore Roosevelt that she says changed her life and inspired the title of her book, Daring Greatly:

"It's not the critic who counts; not the man who points out how the strong man stumbles or where the doer of deeds could have done them better. The credit belongs to the person who is in the arena. Whose face is marred with dust and sweat and blood; who strives valiantly ... who at the best knows in the end the triumph of high achievement, and who at the worst, if he fails, at least fails while daring greatly ..."

After reading that quote, Brown says it made her realize three things. First, she wanted to be the person in the arena. "If we want to be courageous and we want to be in the arena, we're going to get our butts kicked," she says. "There is no option. If you want to be brave and show up in your life, you're going to fail. You're going to stumble. You're going to fall. It's part of showing up."

The second thing she realized is that comments from "Twitter thugs" -- people who never risk anything but criticize the people who do -- don't matter. "If you are not in the arena also getting your butt kicked, I'm not interested in your feedback," Brown says.

The third thing culminates everything Brown has learned over the past 12 years of studying shame and vulnerability. "Vulnerability is not about winning, it's not about losing -- it's about having the courage to show up and be seen," she says. "It's about willingness to say, 'Look, I don't have all the answers.'"

If you're afraid to be vulnerable, Brown says you're not the only one - but there is something even more terrifying.

"I think being vulnerable feels dangerous, and I think it feels scary, and I think it is terrifying," she says. "But I don't think it's as dangerous, scary, or terrifying as getting to the end of our lives and wondering, what if I would have shown up?"

"That, to me, is what daring greatly is," Brown says.

"Oprah's Lifeclass" airs Sundays at 9 p.m. ET on OWN .