Imagine you’re 17 years old. You’re surfing the web, procrastinating. You’re just passing the time on YouTube, watching inane videos and knowingly letting yourself rappel down into the rabbit hole of the internet. It’s nothing out of the ordinary, thousands of people are doing the exact same thing you are right at this exact second.

Except, in all likelihood, when you click a video plainly titled “THE WORLD’S UGLIEST WOMAN,” you won’t see your own face looking back at you.

This is what happened to Lizzie Velasquez, now 26 years old. Velasquez has a rare congenital condition, so rare that it doesn’t even have a name. It affects her vision and her immune system, among other things, but its most obvious impact is on her body. Velasquez has zero percent body fat, and is unable to gain weight.

While she’s been bullied by forces seen and unseen — cruel playground taunts, strangers sneering on the sidewalk, commenters on that YouTube video telling her to do unspeakable things and calling her unrepeatable names — instead of retreating into herself, Velasquez has taken full ownership of her own story and turned it into a force for good. She started a YouTube channel and began vlogging, delivered a TED Talk that went viral and even spoke before Congress in support of anti-bullying legislation.

And now, at this year’s South by Southwest Film Festival, Velasquez took yet another step forward in her personal journey with the debut of “A Brave Heart: The Lizzie Velasquez Story.” Velasquez is the subject and executive producer of the feature documentary, which chronicles her life and her impact on the world.

As I sat down to chat with Velasquez at the Four Seasons in Austin ahead of a panel she would lead with fellow YouTuber iJustine, we were immediately interrupted by an older man who had seen the premiere of “A Brave Heart” the afternoon before and wanted to congratulate Velasquez and say how much her story inspired him.

It’s an occurrence that’s becoming more common for Velasquez, who said of the standing ovation she received the day before, “I think I’m still speechless from it.”

Though this was the first time her documentary has gotten a stranger to come up and say hello, it’s hardly rare otherwise.

“I get a lot of it still from my TED Talk, actually,” she said. “It happened to me this morning. A girl came up to me and said, ‘I saw your TED Talk for the first time.’ So it’s been a mixture. The gentleman who just came up, that was the first time that’s happened.”

That’s not even to mention the more than 314,000 subscribers to her YouTube channel, who consider her a friend and ally. She plays with her dog, chats with her parents and often speaks directly to the camera about her day and the things she’s excited about.

“I don’t know these people, but turning on my camera and pressing record is like opening a small window into my life for people who might need a friend or who are watching my videos because they don’t have a social life or are stuck at home or whatever they may be, and because of that, it makes me feel good to share my life,” she said.

Velasquez is so positive, in fact, that if she met the person who originally posted that YouTube video labeling her the world’s ugliest woman, the one that went viral and inspired hundreds of pages of comments calling Velasquez vile names, she would thank him.

Yes, she would thank the person who posted something that made her cry on her bedroom floor for days and make her fear for her life. Because without the video, who knows what her life’s work might have been? She’s not only forgiven the poster, she sees a positive ripple from their actions. They changed her life, she changes the lives of thousands others through her vlogs, her appearances and now through “A Brave Heart.”

“I would absolutely say thank you,” she said. “Absolutely. Because if I never found that video, it wouldn’t have been the spark to change everything. I think I’d still be in a way helping people but I don’t know if it not the same way as now. I wouldn’t be mad. I’d be so grateful, which sounds so crazy. It changed everything.”

Here's what Velasquez said when asked to share her tips for walking through the world with confidence.

Be yourself.

As it turns out, the oldest advice in the book is also the most effective. "You have to be fully aware and confident that you are enough just being you," Velasquez said. "That’s enough! You don’t have to live up to anyone else’s standards, you don’t have to look like anyone else, you don’t have to compare yourself to anyone else. You being you is enough, and you putting your positivity and good vibes out into the world, once you get to that point absolutely everything will fall into place. Whether it’s your personal life, your work life, your school life, your confidence, everything will fit once you believe in yourself."

Roll with the punches.

"It’s been my style for so long to just roll with the punches and whenever something comes up you get, really, to just tackle it and enjoy it," she said. "I actually made up my TED Talk as I was going. I had it planned for three weeks, and as I was walking up onstage I looked at [the TED organizers]. I was like, 'listen, don’t freak out. I just need you to trust me, but I’m changing everything we planned.' She looked at me with big eyes and took a deep breath and said, 'I trust you.' So I walked up and told myself to pretend you’re talking to your best friend." Velasquez's TED Talk has millions of views.

Love yourself.

"A few years ago I did this thing that I now call the Love Yourself List, where I wrote down everything that I love about myself, whether it’s physically or my personality," she said. "I posted the list on my bathroom mirror to where I would see it every single day and I read it until I believed it instead of just looking at the words. And every time I would compare myself or doubt myself, I would think of the list and think, ‘these are the things I do love about myself. And over time, the list worked and I believed it."

Fake it until you make it.

As a junior in high school, Velasquez's principal asked her to speak to 400 9th graders about her experience. After she gave the talk, however, she caught the bug and wanted to become a motivational speaker.

"I went home and googled 'how to be a motivational speaker' and made a website and jailed people and said if you need a speaker, I’m your girl. I didn’t tell that that I’d only done one speech ever and didn’t know anything. I just wasn’t going to go wait around for it. I taught myself...I’m not going to wait until someone asks me to go, I’m going to go, ‘here I am!’"

It's OK to have bad days. You SHOULD have bad days.

"I make it a point to let myself have bad days on a regular basis," Velasquez said. "There were many times when I wouldn’t get it out of my system. I wouldn’t let myself cry and wouldn’t sit in a quiet room and just reflect or take my dog for a walk and leave my phone inside. I wouldn’t do all of those things and over time you just build up and at a certain point it builds up and explodes, probably at the worst time possible. I make it a point to let myself be sad today and say 'why me' and cry and complain and leave my blinds closed, but tomorrow, it’s done. Tomorrow, I’m not going to feel sorry for myself, I’m opening my blinds, I’m getting out of bed, and I’m letting myself be happy. It’s worked! And now I can’t picture myself not doing those things because it’s what keeps me sane."