Napoleon Hill's classic "Think and Grow Rich" is a favorite of many highly successful people.

In the 1937 bestseller, Hill shares what he learned from studying 500 millionaires, including Andrew Carnegie and Charles Schwab. The book outlines ways to re-imagine how you think about time, money and relationships.

In an interview at CNBC's iConic conference in New York, Daymond John, the successful entrepreneur behind fashion brand FUBU and investor on ABC's "Shark Tank," said he learned one of his top productivity tricks from Hill.

Daymond John

"I do goal-setting," John tells CNBC. "The first time I read about this was in Napoleon Hill's 'Think and Grow Rich,' I was 16 years old."

At any given time, he explains, he has a list of 10 goals, each of which have deadlines.

"Six of them expire in five months," John explains, "one expires in fives years, one expires in 10 years and one expires in 20 years."

These goals are different from daily to-do lists, errands or appointments. They are bigger and pertain to self-improvement. About every six months, John adjusts his goals depending on what he's completed or new projects he's considering.

"I read them every night before I go to bed, so it's the last thing I think about," he says. "And I read them every morning when I wake up."

Writing down your goals can help you visualize what you want to accomplish and figure out the steps you need to take to achieve them. Rereading them reminds you to use your time efficiently to accomplish them.

The strategy, John says, keeps him motivated and on track to achieve his goals.

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