Billionaire rocket man Elon Musk says starting a company is like “eating glass and staring into the abyss.”

“It’s very difficult to start companies and quite painful,” Musk once told a group of students visiting SpaceX. Being an entrepreneur whose life goal is to save the human race and rocket it to Mars sounds painful indeed. “It’s not going to optimize your leisure time.” No, not when you run your own company, let alone three. There’s no time to unwind and lick your wounds.

But, hey, if you work glass-eating hard, make the best of it and whistle while you work. Musk does. (Watch him wet his whistle here, at the 13:19 mark.) Also, play some zany tunes to stay focused, maintain a sense of humor and avoid “boring corporate” situations.

Related: Times Elon Musk Said and Did Things You Wish You Could

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Here are five weird and wacky songs Musk says he listens to for inspiration, in the order in which the real-life Iron Man presented them. He shared this odd batch of surprising licks on Los Angeles public radio station KCRW a few years back, when he guest DJed. But first, a warning: Two of them aren’t exactly safe for work, well, not maybe not unless you work at SpaceX, Tesla or SolarCity.

1. “Fly Me to the Moon” -- Frank Sinatra

Why it inspires Musk, in his own words: “I like the sense of possibility and it’s really inspiring. And I’d really like to fly to the moon. … You know, obviously I own a space company, I’m going to tend to like something that involves flying to the moon. You hear this song and it sounds like it’s really going to happen.”

Related: 7 Takeaways in the Success of Elon Musk for Young Entrepreneurs

2. “Always Look on the Bright Side of Life” -- Monty Python

Why it inspires Musk, in his own words: “It’s from [the Monty Python film] Life of Brian and obviously it’s a pretty funny song because [the characters] are being crucified at the time. But I think it is a good reminder not to get focused on the negative things in life. And my personal philosophy is I’d rather be optimistic and wrong rather than pessimistic and right."

3. “America, F*ck Yeah!” -- Team America: World Police

Why it inspires Musk, in his own words: “That is from the movie, Team America. I’m a big fan of South Park. The shows that I watch -- South Park, Daily Show and Colbert Report -- those are sort of my main three ones -- they just capture a little bit of essence of America in both a good and a bad way.”

4. “Con Te Partiro” -- Andrea Bocelli

Why it inspires Musk, in his own words: “I think that song is kind of a reminder that the world is a beautiful place. It’s an incredibly beautiful song, sung really beautifully, so I think that’s why it makes me feel that way about the world.”

Related: 16 Blood-Pumping Songs to Boost Your Motivation and Confidence

5. “Santa Claus Is Coming to Town” -- Fred Astaire

Why it inspires Musk, in his own words: “I personally don’t understand it, but it’s the song that I whistle the most. I don’t even realize I’m whistling it. I just go into auto-whistle and this one comes up more than any other so I must like it at a subconscious level, but I’m not entirely sure why. I could guess. It’s sort of a positive song. I mean, who doesn’t like Santa Claus? I guess it’s good to have him come to town.”

Oh, and one more for the list, while we’re at it. It’s not one of Musk’s picks, but it’s all about the man, the myth, the entrepreneurial legend. Get an earful of “Elon: Champion for Humanity,” by Raptor Command, a shredding “heavy metal tribute to Elon Musk.” Rock on, Rocket Man.

If you haven't had enough Elon, “one to lead us all,” get a load of this goofy cartoon version of the song.

KCRW’s Guest DJ Project