As Fortune reports in a new feature story this week, employers are increasingly looking beyond traditional credentials to find job candidates whose life experiences show their “grit.” That term is loosely defined as courage, perseverance, resilience, creativity, a knack for problem-solving and an openness to learning—and it may be a better proxy for success than any posh internship or Ivy League degree.
For examples of people whose grit propelled them to the top, you may not have to look any further than the corner office. Complex challenges early in life helped these six current and former chief executives develop skills that got them to the pinnacles of their professions.
Oprah Winfrey, CEO, Harpo Entertainment
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The media mogul has mined her life story—poverty, despair, and sexual abuse starting at age 9—as a source of strength to push through professional barriers, and to inspire millions to do the same. “The reason I’ve been able to be so financially successful is my focus has never, ever for one minute been money,” she says.
Ursula Burns, Chairwoman, VEON; Former CEO, Xerox
Her family was so poor that her single mother traded office cleaning for health care. But Burns’ early aptitude for math won her a scholarship and an internship at Xerox xrx , where she would compete her way to the top. “I’m a black lady from the Lower East Side,” she says. “Not a lot intimidates me.”
Howard Schultz, Executive Chairman, Starbucks
Schultz grew up in public housing in Brooklyn, surrounded by poverty, and was the first in his family to go to college (on a football scholarship). After training in sales, he launched the company that would later buy Starbucks sbux . “In the course of the year I spent trying to raise money, I spoke to 242 people, and 217 of them said no,” he says.
Sean Combs, CEO, Sean John
Combs launched a generation of hip-hop talent and made a lasting imprint in fashion. But his story could have turned out much differently: His drug dealer father was killed when he was 3. “It made me work even harder,” he recently tweeted. “We never got to share the moments that made me a man … but he lives in my spirit.”
Satya Nadella, CEO, Microsoft
Nadella was climbing the ranks at Microsoft msft when life complexity hit. Zain, the eldest of his three children with wife Anu, was born quadriplegic and visually impaired. “It has had a profound impact on how I think, lead, and relate to people,” he has said, moving empathy and resilience to the forefront of his thinking.
Geisha Williams, CEO, PG&E
Her parents fled Cuba when Williams (née Jimenez) was 5; by 7, she was her parents’ main translator in talks with lawyers and accountants at groceries they owned in New Jersey. Mentors encouraged her early on: “I went from thinking I could be a manager to thinking I could do something much bigger,” she told Fortune.
A version of this post appears as a sidebar in the article “How Your Life Experience Could Help You Land a Great Job” from the Feb. 1, 2018 issue of Fortune.