Lizzie Velasquez on Choosing to Fight Bullies: 'I Wanted To Have Control Over What I Showed People Who I Was'

— -- When Lizzie Velasquez clicked on a video called “The Ugliest Woman in the World,” her life changed forever.

“I decided to go look for music on YouTube and that’s when I found it,” she said. “I don’t even know why I clicked on it, but I did, and that’s when I lost it.”

Unexpectedly, she was the subject of the video.

The video had 4 million views and thousands of comments where Velasquez said people were “calling me a monster or asking why my parents didn’t abort me… ‘just pick up a gun’… ‘I wish you were dead.’”

Watch the full story on "Nightline" tonight at 12:35 a.m. ET

All her life, the 26-year-old has suffered from Marfan Syndrome and Lipodystrophy, making it impossible for her to gain weight. Velasquez said she endured years of bullying because of her uncommon appearance, everything from nicknames like “skinny bones,” “grandma” or “pork chop legs,” to questions like, “why do you look like that? What’s wrong with your face?”

When she saw the “Ugliest Woman in the World” video, Velasquez said she was “unbelievably crushed,” but then she decided to take a stand.

“It was a long process of being really sad, then being really angry, then saying, ‘I need to take this into my own hands. How can I turn it around?’” she said. “ It was scary. But I wanted to have control over what I showed people who I was.”

Velasquez began speaking out against the hateful comments, starting with uploading her own response video to YouTube, where she held place cards to describe her feelings and then revealed her face at the end. Then she started researching how to become a motivational speaker.

“I completely taught myself everything that I know about speaking via the internet and YouTube,” she said. “I studied speakers' websites. I studied if they walked which way across the stage. If they had note cards, if they had slide shows… Anything I could get my hands on, that's what I would learn.”

In December 2013, Velasquez delivered a moving and masterful “TED X Talk” about how she refused to let her experiences with bullying define who she was. The video went viral on YouTube and earned more than twice the views the “Ugliest Woman in the World” video received. Her story strongly resonated with people around the world.

Velasquez’s parents, Lupe and Rita Velasquez, have been with her through every step. Rita said that when her daughter was born, the nurses first showed her a picture of her daughter before they allowed her to hold Lizzie.

“[They] were worried that I was going to freak out by seeing her,” Rita said. “And so, they took a Polaroid picture of her, and I just said, ‘I need to be with her.’”

Lupe Velasquez said he was in love with his daughter the moment he saw her.

“It didn't matter, you know, what we were going to go through, she was our baby,” he said. “And she was our child. I was just happy and excited. And I just couldn't wait to share her with the world.”

It wasn’t until Lizzie started school that she realized how different she was.

“I couldn't understand why other kids didn't like me or why they were hesitant to be around me,” she said. “So going into school, I never had that thought of, ‘What am I going to do if somebody doesn't want to sit by me or be nice to me, even though I haven't said anything to them?’”

But she refused to let the bullies win, nor would she let the fear of failure stop her from trying new things, including cheerleading.

“When I wore that uniform around campus, I felt like it was my superhero cape,” she said. “I felt like it was my disguise to get out of my Lizzie body and to be a cheerleader who is just like everybody else.”

Now Lizzie Velasquez is a superstar on YouTube, imparting wisdom on her half million subscribers. Her message of strength has even inspired celebrities. Two weeks ago, Kylie Jenner wrote about her own painful experience with bullying on her Instagram account, saying, “people are so quick to say horrible things about me every day over and over and sometimes I can’t take it… I breakdown, I die, I cry… Lizzie you are so strong and I admire you so much.”

“For her to take her incredibly huge platform to be able to say, ‘This is Lizzie. I was able to relate to her,’ And for her to be able to be vulnerable in an Instagram post with millions of followers, I think is incredible,” Velasquez said.

Velasquez’s fans come from all walks of life, but it’s the young students enduring bullying at school that often relate to her the most.

McKenna Biliti is a 15-year-old high school sophomore who said she endured bullying and she started watching Velasquez’s videos to give her much needed strength at a critical time.

“[Velasquez] chose to be happy when she had the choice to give up… and now I’m starting to realize that I can be like that and it’s a lot easier than I thought it would be,” McKenna said.

Which is why when McKenna actually met Lizzie Velasquez by chance outside of her high school, she broke down in tears.

“I just told her that she’s one of the main reasons that I’m still here today and she’s helped me through so much without even realizing it,” McKenna said. “I was ready to give up at that point when I found her motivational speaking videos, and I was watching them and the words that she said were just so inspiring.”

It’s stories like McKenna’s that motivated Velasquez to lobby for anti-bullying legislation on Capitol Hill, even while dealing with debilitating health issues.

While Velasquez’s illnesses are by no means terminal, she does have a heart condition that has to be monitored closely for the rest of her life. All of this is documented in a new movie about her life called, “A Brave Heart,” which was directed by Sara Hirsh Bordo and produced by her company Woman Rising. It will be released on Friday but is already winning awards at eight different film festivals.

When asked who her hero was, Velasquez became emotional and said it was hard for her to pick just one person.

“Every person that I hear from on a regular basis, people like McKenna, those are my heroes because they are just everyday people who are struggling,” she said. “And I know what that's like… I can read their emails and read their pain and know what they're going through. But by the end of it, I can feel them smiling. And I don't see it as I was able to do that. I see that as I am so proud of them because they were able to do that for themselves. And if they can do that, I can do this."