The actress tells the magazine she was born with several health issues – including kidney dysplasia that resulted in her receiving a kidney transplant using a donor kidney from her father.
"I was born with so many health issues that doctors told my mother I would never have a normal life," she recalled.
"And she said, 'You're right, she won't – but it won't be because of her health.' When my mother told me that story, it resonated with me: If I can't have an ordinary life, I might as well have an extraordinary one. If you set your mind to something, you'll achieve it."
Sarah's certainly done more than plenty of 24 year olds have! She has a starring role in award-winning comedy series Modern Family as Haley Dunphy, and has appeared in a string of movies.
"Happiness, I've learned, comes from within," she tells the mag. "I am happiest when I am doing something I love. And I love Modern Family – it's the best job I've had in my 20 years as an actress. It didn't come easily or fast or free: It took me 14 years to land a gig like this."
Sarah is loving life right now but she didn't have the easiest of times last year. She was groped by a fan in Australia in 2014 and later that year applied for a restraining order against ex-boyfriend Matt Prokop.
Now she's happy with new man Dominic Sherwood.
Sarah says: "When you're feeling vulnerable, it can lead to doubt and second-guessing. It will steer you away from your goals and your happiness. Once you have a goal, keep moving forward – even if you're taking baby steps!"
The new issue of Seventeen magazine is on newsstands 21 April. Check out more from the issue at www.seventeen.com
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