You don't get to be a self-made billionaire without a lot of hard work, and the most famous billionaires are as well known for their drive and heavy work schedules as they are for their riches. But even the most driven billionaires need to unwind.

How do they do it? We took a look at what three of the world's most high-profile entrepreneurs do to relax. What's most striking is this: The things they do to rest and recharge are simple things that cost little or nothing and that any of us can do at home. So next time you need to recover from the stresses in your life, consider any of these simple approaches. Tell your family and friends you're relaxing like a billionaire.

1. Bill Gates plays bridge.  ​

In fact, he often plays against his buddy Warren Buffett. Buffett once said, "If I'm playing bridge and a naked woman walks by, I don't even notice." As for Gates, although he admits he's not the world's best bridge player, he competes in tournaments when he can, sometimes by computer, for example in the Online Bridge World Cup. "It's the best exercise there is for the brain," he has said. 

Gates and his family also love to play a civilization-building strategy board game called Settlers of Catan. He says that he, Melinda Gates, and their kids have spent many hours "trading resources, building roads, and strategizing to be the first to reach 10 victory points." Both games are smart ways to unwind since research has shown that playing games appears to bring brain benefits.

2. Warren Buffett plays the ukulele.

In addition to bridge, one of Buffett's ways to relax is by playing the ukulele. Though he's clearly not an expert musician, he is a bit of a ham, and he often plays and sings at Berkshire Hathaway board meetings, charity events, and media appearances. Here's one where Buffett, his son Peter (who is a professional musician), and the Senegalese-American singer Akon collaborate on "Ain't She Sweet."

This is another very smart choice because multiple studies show learning to play a musical instrument has brain benefits that can counteract the effects of aging. And the ukulele, one of the easiest instruments to play and one of the most inexpensive to buy, is a great place to start.

3. Mark Cuban does cardio and watches Law & Order.

Cuban is no couch potato. According to Business Insider, he does an hour of cardio six days a week, which can include playing basketball, using elliptical or stair machines, or taking kickboxing or Latin fusion classes. And when he's not working out, Cuban is famously driven, saying he sometimes will wake up and work in the middle of the night if an idea comes to him.

But when winding down before sleeping, he does what many Americans do: He watches television in bed, Business Insider says. Specifically, Law & Order. Experts warn that watching TV in bed can disturb your sleep, but the biggest danger seems to be falling asleep with the TV still on--the light and sound from the set means your sleep will be disturbed and less restful than it should be. Cuban's got that handled, though, because he has a timer set to turn the TV off when the show is over.

Law & Order isn't Cuban's only viewing addiction. He also loves disaster movies. When Paper City asked him to name his favorite actor, he answered, "The star of any end-of-the-world flick. I love watching cities get destroyed." That's one way to channel pent-up aggressions.