Why Amanda Seyfried decided to finally seek help for her anxiety disorder.

She’s been in major blockbuster films since she was a teenager, is a red carpet regular and is now starring on Broadway, but for Mamma Mia actress Amanda Seyfried, the thought of getting up in front of large audiences has always been paralysing.

So paralysing in fact, that she admitted in a 2012 interview with David Letterman that she had “never done a live interview before noon without some sort of liquid courage.”

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Confessing she was drunk at the time, it was that interview that proved to be a turning point in Seyfried’s life. She vowed to begin dealing with her anxiety.

“[The drinking] made it fun for me, but then I watched it and was like this is not what I want to promote about myself,” she recently told US Vogue.

Not long after, she started seeing a counsellor to seek help in getting over what had become a debilitating fear. (Post continues after video.)

“I have a lot of anxiety that I’ve been struggling with my whole life,” she says.

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“So I have been working through it. I’m terrified, but this is exactly what I wanted.”

The 29 year-old has spoken about her anxiety before, revealing in a 2013 interview with UK morning show Lorraine how important she believes it is to raise awareness about it.

“You know, I wish I knew it was possible to get through it, because at one point I didn’t think there was another side. I mean, you can be.. .it can paralyse you,” she said. (Post continues after gallery.)

“Fear, unrealistic fear. But we’re human, and we’re really strong,” she concluded.

Unfortunately, Seyfried is not alone. Anxiety disorders affect 1.3 million Australians each year, with almost half a million sufferers aged between 16 and 24 years-old.

Several other celebrities have spoken about their battles with anxiety, including Emma Stone and Scarlett Johansson.

RELATED: Lena Dunham: ‘Exercise has helped with my anxiety in ways I never dreamed possible.‘

Stone revealed in a previous interview with Vogue that her panic attacks started when she was just eight years-old.

“I was just kind of immobilised by it,” she said.

“I didn’t want to go to my friends’ houses or hang out with anybody, and nobody really understood.”

Stone said she still gets panic attacks sometimes but  has learned to channel her fears into her work, as well as turning her attention to calming tactics like baking, which make her feel like she's in control.

More recently, Lena Dunham shared how exercise had dramatically helped her with her anxiety in ways she "never dreamed possible".

In an instagram picture of her doing Acro yoga, Dunham wrote: "To those struggling with anxiety, OCD, depression: I know it's mad annoying when people tell you to exercise, and it took me about 16 medicated years to listen. I'm glad I did. It ain't about the ass, it's about the brain. Thank you @tracyandersonmethod for showing me this light... #notsponsored #stillmedicated" (Post continues after gallery.)

Anxiety can feel paralysing, debilitating and all-consuming, but if there's one lesson to be taken away from these celebrities' experiences it's this: there are solutions.

You're not alone and it won't always be like this. Don't be afraid to ask for help. If you know someone who suffers from anxiety, there are ways you can help too.

If you or a loved one is experiencing significant distress, the number for Lifeline is 13 11 14. Call them any time.