Theranos founder Elizabeth Holmes gave a great interview to Maria Shriver last week at the Vanity Fair New Establishment Summit.

Amid a lot of interesting thoughts, what stood out to me was her single-mindedness and commitment to her mission. She’s defining her life around making sure fewer people say premature goodbyes to their loved ones. Theranos currently offers discounted medical tests direct to consumers at Walgreens in Arizona, and plans to expand globally. Holmes, now 31, founded Theranos when she was 19 and dropped out of Stanford the next year.

When asked the advice she’d give anyone wanting to launch an app or company, she nailed the importance of passion and obsession.

“Make sure it’s something that you love so much that even if you were fired you would do it over and over and over again because you’ll build it differently,” said Holmes, who wears black turtlenecks everyday to simplify her life so she can focus on work. Her success illustrates the importance of being obsessed if you want to launch a disruptive start-up. That enthusiasm helped her move past the inevitable failures.

“I knew that I wanted to spend my life doing it, and I wanted to spend my life trying. And I had absolutely no idea how we would do it. But I knew that this was what I wanted to work on and I felt like this was what I was put on this earth to do,” Holmes said. “The purpose of school to me was always to learn the tools to be able to pursue what you love. And I felt like I had those tools to be able to now go obsess over what it was I wanted to be doing no matter what.”

Holmes was happy to work out of the spotlight for years developing the Theranos product, which delivers blood tests from a finger prick rather than a full vial of blood.

She also made an interesting comparison between our access to firearms and to medical tests.

“In this country we can still go buy weapons and kill ourselves but we can’t buy access to our own information directly without going through a physician,” Holmes said.

You can watch the whole interview below. For more on Holmes, check out this New Yorker profile.