The Help star suffered from debilitating anxiety and by the time she was seven-years-old, her mental state and frequent panic attacks were affecting her everyday routine.

"My brain (would) naturally zoom 30 steps ahead to the worst-case scenario," she tells Rolling Stone magazine. "When I was about seven, I was convinced the house was burning down. I could sense it. Not a hallucination, just a tightening in my chest, feeling I couldn't breathe, like the world was going to end.

"There were some flare-ups like that, but my anxiety was constant. I would ask my mum a hundred times how the day was gonna lay out. What time was she gonna drop me off? Where was she gonna be? What would happen at lunch? Feeling nauseous. At a certain point, I couldn't go to friends' houses anymore - I could barely get out the door to school."

Emma's parents started taking her to therapy and they soon started to see a change in their daughter's behaviour.

"It helped so much," she says. "I wrote this book called I Am Bigger Than My Anxiety that I still have: I drew a little green monster on my shoulder that speaks to me in my ear and tells me all these things that aren't true. And every time I listen to it, it grows bigger. If I listen to it enough, it crushes me. But if I turn my head and keep doing what I'm doing - let it speak to me, but don't give it the credit it needs - then it shrinks down and fades away."

The 28-year-old also found solace in performing as a young girl and discovered improvisation and comedy helped her overcome her troubles.

"I started acting at this youth theatre, doing improv and sketch comedy," she continues. "You have to be present in improv, and that's the antithesis of anxiety."

At the age of 14, Emma decided she wanted to drop out of high school in Arizona and in 2004, she moved to Los Angeles with her mum to pursue her career in Hollywood.

Things initially didn't go as planned, but she was able to make it work in her favour and her career eventually took off.

"I did an episode of Malcolm in the Middle," she recalls. "And an episode of Medium. I was the voice of a dog on The Suite Life of Zach and Cody."

And her working relationship with casting director Allison Jones proved to be crucial.

"I auditioned for Allison for three years," she explains. "She would bring me in for things and they'd never work, but then one Friday evening she called me and said, 'Hey, my office isn't even open tomorrow, but I want to put you on tape for something.' It was Superbad."

The comedy led to Emma landing roles in films like Zombieland and Easy A, and now the actress is in high demand, drawing critical acclaim - and Oscars speculation - for her new movie musical, La La Land.