By: Sarah Hedgecock

“What’s the thing you love, and that you’re so incredibly passionate about that if you got fired you’d still want to do it?” Elizabeth Holmes asked a room of 1,500 people on Monday.

She was speaking at this year’s Forbes Under 30 Summit in Philadelphia, accepting the Under 30 Doers Award for her work trying to make expensive lab tests — and, possibly more importantly, test results — accessible to everyone. ”We believe that transparency empowers the individual and empowering the individual will change the system,” she explained in an interview with Forbes senior editor Matthew Herper.

Holmes, 31, ranked #121 on the Forbes 400 list this year and is the youngest self-made female billionaire in the world. She made her fortune through her company, Theranos, which produces blood tests that can allegedly test for multiple diseases using a fraction of the blood required by more standard tests. It also sells them at at a lower cost: Theranos has over 200 tests priced under $10.

Holmes didn’t always know her calling was in blood tests. Her father worked for USAID, and she says watching him and his colleagues growing up made her realize she wanted to change people’s lives. Starting a company just seemed like the best way to do it.

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