You can become an expert in just about anything if you read enough books on the subject. If you don't believe me, ask Elon Musk. Whenever anyone asks him how he learned to build space-traveling rockets, this is his three-word answer: "I read books." 

Musk is no rocket scientist, at least not by training. He has a bachelor's degree in economics and another one in physics, and although he got into Stanford's PhD program in energy physics/material science, he dropped out after two days to launch Zip2, a city guide software company that the founders sold to Compaq for $307 million. A few years later he co-founded the company that would become PayPal, which eBay bought for $1.5 billion. 

It was at this point, flush with internet millions, that Musk began setting his sights on colonizing Mars. He attempted to buy rockets from the Russians, but they demanded a price even an internet millionaire couldn't afford, and generally refused to take him seriously, according to a profile in Esquire. So Musk told aerospace consultant Jim Cantrell who was working with him that they would build the rockets themselves. 

He showed Cantrell his plans, and Cantrell thought, "I'll be damned -- that's why he's been borrowing all my books." Musk had been ingesting Cantrell's textbooks on rocket-building and had transformed himself into an expert. "He knew everything," Cantrell told Esquire. "He'd been planning to build a rocket all along." And that's how SpaceX was born.

It works even if you're not Elon Musk.

"All right," you might argue, "Musk learned to build rockets by reading books. But he's a genius. Ordinary mortals can't do this." But they can, at least they with can houses, if not rockets. I know, because my father-in-law, an otherwise unremarkable man who spent most of his adult life working for the Postal Service, did just that.

I never met him; he died a few years before my husband, Bill, and I got together. But Bill remembers how his father (also named Bill) rebuilt the family home piece by piece over the years, reconfiguring it as needed. He brought in fill and raised and leveled the yard. He built on new rooms and added a wheelchair ramp for his granddaughter. When he wasn't rebuilding his own house, he was helping the neighbors renovate theirs. He could have had a successful contracting business if he'd been willing to give up the steady paycheck of a civil servant. Bill senior never took a course -- he just read books about whatever he wanted to do, and then he went and did it.

Want to read your way to success yourself? Begin with a growth mindset -- the belief that your abilities are not fixed in stone but can change over time, and that you can expand and change them if you're willing to put in the effort. It works for Musk: Someone with a bachelor's degree in economics and physics who believes he can learn to build his own rockets has a growth mindset, and then some. Next, if you can, do what Musk did when he hooked up with Cantrell. Find one or more mentors who can advise you and help guide your learning. At the very least, your mentor can help you figure out which books to read to build greater expertise more quickly. 

And finally, put that expertise to the test. Dan Coyle, who's written several bestselling books about what makes some individuals, and some teams, more successful than others, recommends spending 30 percent of your time learning and 70 percent testing your newfound knowledge. So, to cement your expertise, test your own knowledge, preferably by trying things out in the real world.

That's what Musk did when he began building rockets, several of which crashed or went off-course before he and his team figured out how to fly them reliably. This summer, NASA trusted SpaceX rockets to send astronauts into space from the U.S. for the first time in nine years. It's a huge achievement, and it all began with a big stack of borrowed textbooks.