A 33-year-old billionaire CEO shares the one question he's been asking himself for the past decade

Since founding his company at age 24, Drew Houston has continually asked himself one important question to ensure his continued growth as a leader.

The 33-year-old billionaire founder of Dropbox, the file-sharing and storage service, told Adam Bryant of The New York Times in a recent interview that one of the earliest leadership lessons he learned as a founder and CEO was that it's important to have a "a healthy paranoia for trying to find out what you don't know that you don't know."

To do that, he said has always asked himself - and still does today - this question: In six months from now, 12 months from now, five years from now, what will I wish I had been doing today or learning today?

When it comes to learning, Houston told Bryant that "reading has been essential."

"I have always wondered why people put so much energy into trying to have coffee with some famous entrepreneur when reading a book is like getting many hours of their most crystallized thoughts," he said.

Read the full New York Times interview here.

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