The best -and worst - habits of Mark Zuckerberg, Jeff Bezos, and more successful people

Zuckerberg has made an annual tradition of setting a challenge for himself to complete in the coming year.

His previous challenges have included running a mile every day, reading a new book every two weeks, learning Mandarin, and building an AI for his home.

Zuckerberg routinely checks Facebook, Messenger, and WhatsApp first thing in the morning.

You might excuse the CEO, seeing as he owns the company behind the apps, but even Zuckerberg acknowledges it's a bad habit.

"It's a pretty sad situation, to be honest," he said in a Facebook Live Q&A. "I have contacts and I can't see very well. And before I put my contacts in I often look to see what is going on Facebook.

"I'm very near-sighted," he added, gesturing that he has to hold the phone close to his face.

Amazon CEO Jeff Bezos is one of several ultra-successful people who are fierce advocates for getting eight hours of sleep a night.

"I'm more alert and I think more clearly" after eight hours of sleep, Bezos told The Wall Street Journal in 1999. "I just feel so much better all day long if I've had eight hours."

Bezos spends quality time with his wife, MacKenzie Bezos, and their four children, by clearing his schedule of early morning meetings and eating a leisurely breakfast with them.

"I wanted her to get the best hours of my day," he told The Journal.

Despite being the richest man in the world, Bezos sets an example by washing the dishes at home every night.

"I'm pretty convinced it's the sexiest thing I do," he told Business Insider CEO Henry Blodget.

Bezos has reportedly been heard saying a number of biting, sarcastic, and even downright mean remarks to Amazon employees when he hears something he doesn't like, according to an excerpt from a book about the CEO.

"If an employee does not have the right answers or tries to bluff, or takes credit for someone else's work, or exhibits a whiff of internal politics, uncertainty, or frailty in the heat of battle—a blood vessel in Bezos's forehead bulges and his filter falls away," author Brad Stone wrote in "The Everything Store: Jeff Bezos and the Age of Amazon."

"He's capable of hyperbole and harshness in these moments and over the years has delivered some devastating rebukes."

Some of his cruelest blows, according to Stone, were:

"Are you lazy or just incompetent?"

"I’m sorry, did I take my stupid pills today?"

"Do I need to go down and get the certificate that says I'm CEO of the company to get you to stop challenging me on this?"

Mark Cuban said he reads more than three hours a day, a practice he has maintained since his time at MicroSolutions, the software company he started in the 1980s.

"A guy with little computer background could compete with far more experienced guys just because I put in the time to learn all I could," he wrote in a blog post.

"Of course my wife hates that I read more than 3 hours almost every day, but it gives me a level of comfort and confidence in my businesses," he said.

Cuban exercises regularly, varying his workout with cardio, basketball, and even kickboxing classes.

The daily challenge of completing a rigorous workout provides motivation for Cuban.

"That I will find a way to get it done, I think, reflects how relentless I can be in the business world as well," he told the Dallas News.

Cuban said he watches TV at night before going to bed and sets the television to turn off automatically so he can fall asleep.

"Maybe it's a bad habit," Cuban said on an episode of the Thrive Global podcast. "I think it's an old habit that I just haven't gotten rid of. Where, when my mind was racing so much and I needed to turn off and couldn't, it was a distraction. When I was thinking about work all the time. If there was something else on, just to distract."

Sheryl Sandberg stays organized by writing down tasks in a "decidedly undigital" spiral-bound notebook, according to Fortune's Miguel Helft.

"On it, she keeps lists of discussion points and action items," Helft wrote. "She crosses them off one by one, and once every item on a page is checked, she rips the page off and moves to the next. If every item is done 10 minutes into an hourlong meeting, the meeting is over."

No matter how busy she is, Sandberg leaves work at 5:30 p.m. to have dinner with her two children.

At the table, they share the best and worst moments of their days — a tradition she started with her husband Dave Goldberg, and continued after his unexpected death in 2015.

"We also share something that makes us feel grateful to remind ourselves that even after loss, there is still so much to appreciate in life," Sandberg wrote in The New York Times.

Sandberg says sleeping more was the key to make her days more productive, energetic, and enjoyable.

"When I became a mother, I realized how important sleep was to my children when they were babies, or they were little, and as they were growing up," Sandberg wrote in a blog post for Thrive Global.

"If they missed a nap, if they didn't get a good night's sleep, everything was harder. And if they had a good night's sleep, everything was easy. And I realized that even though I was an adult, I'm the same way."

Now, she's adopted a habit of turning her phone off before bedtime, which, thanks to her children, is an early 9:30 p.m.