From advanced rockets to electric cars, who wouldn't like to know where entrepreneur Elon Musk finds his big ideas?

The SpaceX and Tesla Motors CEO recently shed some light on his his thought process when dreaming up his next huge project. They key, Musk indicated at a Stanford Business School conference, is to identify only those areas that you're certain will have a massive and positive impact. Then get to work on a problem within that space.

"In the case of Tesla, SpaceX, SolarCity, and PayPal… it really stemmed from when I was in college and trying to think: what would affect the future most likely in a positive way?" Musk said. "So the three areas I was quite sure would be positive were sustainable energy, the Internet, and making life multi-planetary." 

The Internet--where Musk experienced his first entrepreneurial success in the late 90s with his search company Zip2--was sure to dramatically affect the future for the better, Musk believed. 

"Previously, communication would have to occur almost by osmosis. You know, from one person slowly through telephone, mail, something like that," Musk said. "Now if you have a nervous system, any part of the human collective can know about any other part instantly."

He added that artificial intelligence and rewriting genomics are two other promising areas. However, he's unsure whether those fields will lead to more harm than good for humanity in the long-run. 

"If you look ahead and say what's really going to have an important impact on the future of humanity as a whole? Those are the five areas that I could come up with standing in the shower basically," Musk said. 

For more on how Musk thinks about the future, watch the video below: