“We each have a responsibility to do something to help the next generation,” she tells Fortune. “You know everyone says how excited they are about me being the first and that’s great. I’m really happy about being the first, but you know what, it’s much more important for me that I’m not the last. I have a job to do to make sure that I’m not the last.”

Williams was five years old when she came to the United States in 1967 with her parents. Fifty years later, Williams was tapped to be chief executive of a company with $17 billion in revenues and 24,000 employees. And she was also ranked on Fortune’s list of the Most Powerful Women in Business.

So what was the secret to her success? “There’s no secret,” says Williams. “It’s hard work, perseverance, having a dream, and following that dream.”

And for women who aspire to being CEO, Williams gives similar advice. “I tell everybody do the tough jobs. Lean in to those difficult positions,” she says. “You learn so much by doing a difficult job. The confidence that you get from doing a difficult job and doing it well is something that you carry to that next position and the one after that.”

Watch the video above to hear more from our conversation with Williams.