• Like Gen Z, this self-made CEO believes in the power of manifesting success—but he insists that visualization alone isn’t enough. It has to be backed by relentless commitment and daily accountability. That’s why, every single night, he asks himself this one simple but revealing question.

What do you ask yourself before bed? Some list things they’re grateful for. Others frantically run through their never-ending to-do list. Sheldon Yellen, CEO of Belfor, rates his productivity for the day—and urges Gen Z career starters to do the same.

“Every night, when I’m getting ready, washing up, brushing my teeth, I look in the mirror—I physically look in the mirror—and answer one question every night,” the $3 billion-a-year disaster recovery chief exec explains his daily high-performance habit to Fortune.

“That question, it’s a simple question, but it’s a difficult answer: How productive were you today? I ask myself that question every single night and I answer it as honestly as I can.”

Yellen then gives himself a score (1% being the worst)—and he says, he wouldn’t be able to sleep if he got bottom marks. “I’d start working,” the self-made billionaire adds.

“When I mentor young people, I tell them: ‘Every day is your day. Today is your day. But when you look in the mirror tonight, how much of it did you actually make count? Were you productive for 65%? 72%? 81%?”

You are the master of your own success

Of course, the evening exercise is easy to cheat—after all, it’s not a real exam, and you’re the one keeping score. But it serves as a powerful reminder that your success is in your hands.

Yellen is a prime example of this: Growing up in poverty, he started working as a dishwasher at just 11 years old in a Coney Island diner before getting a gig at an affluent men’s health club, Southfield Athletic Club, in Detroit.

“I started out shining shoes and cleaning toilets, urinals and the shower area, and I did the laundry,” the 67-year-old recalls.

“I took full advantage of these opportunities to do whatever I was doing the best I could do. I believed that if you did it long enough, somebody would notice—and they did, and so more opportunity kept presenting itself to me at a young age.”

After dropping out of high school, Yellen says he worked seven days a week—including “on the streets”—to turn his life around. He shined shoes, washed cars, chauffeured entertainers in limousines, and hustled until he landed in the restoration industry at 26 years old.

Since then, he’s climbed the ranks at Belfor (then known as Inrecon) from its 19th employee to CEO of around 12,000 employees worldwide.

Under his helm, Belfor has become the world’s largest disaster recovery company—it receives around 330,000 callouts a year to deal with the fallout from hurricanes, flooding, terrorist attacks, and more. Over the course of four decades at the company, Yellen has overseen the clean-up after 9/11, Hurricane Katrina, and the 2011 Thai floods, to name a few.

“I believe if you lay down at night and you dream it and you visualize it, and then believe it, you can be it—I really do,” Yellen says of his impressive journey to the top. “I came from a family raised on welfare. There was no guarantee I’d be where I’m at. I dreamt. I visualized it. I hear it in song. I believed it. I still believe it.”

But of course, visualizing success—which Yellen describes as mapping out a path forward—is just one piece of the puzzle.

“All that’s needed is the commitment,” he adds. Like holding yourself accountable every night and reviewing your productivity with complete honesty.

“Now, you got to have patience. It doesn’t happen overnight, but if you’re committed and you get others to believe in your commitment, they will help you along.”