Elon Musk is a very busy man. He runs Tesla Motors, designs spaceships and oversees the burgeoning privatized space program at SpaceX and somehow still manages to visit Mashable’s offices and even make the occasional Daily Show appearance. How does he do it? Serial entrepreneur and billionaire Musk offers his secrets to the highly effective exec.

Email.

Yup, that’s it. Or so it would seem. Musk is evidently proud of his “mad” email skills. He couldn’t exactly offer us productivity tips, but did say "I do love email. Wherever possible I try to communicate asynchronously. I'm really good at email."

I guess Musk has to be as he literally splits his time between SpaceX, which is preparing to send an unmanned spaceship to the International Space Station on April 30 and Tesla Motors, which is preparing to roll out a luxury electric motor sedan later this year.

For Musk, the secret to making this work is having a very regimented schedule. Here’s what Musk’s typical week looks like:

Monday: He’s at SpaceX in Los Angeles

Tuesday and Wednesday: Tesla in Palo Alto, Calif.

Thursday and half of Friday: Back at SpaceX

Remaining half of Friday: At Tesla Design Studio, which is adjacent to SpaceX

Weekends: With family

Maintaining a tight schedule makes sense for such a busy guy, but how does the low-key exec who was born 40 years ago in South Africa make it all work?

“I've actually not read any books on time management," admitted Musk.

Instead, he combines his tight schedule with a focus on productivity. He’s constantly trying to optimize his time. “I think it’s very important to have a feedback loop, where you're constantly thinking about what you've done and how you could be doing it better. I think that's the single best piece of advice: constantly think about how you could be doing things better and questioning yourself."

There you have it:

Email

Scheduling

Productivity

Feedback

Self-Improvement

You can thank us later.