Since 2013, Vishen Lakhiani says he's interviewed more than 1,000 self-help experts — and his most important takeaway has nothing to do with sleep habits or performance tricks.

Lakhiani, 45, is the founder and CEO of online learning platform Mindvalley, which offers masterclass programs and live interviews from leading health and wellness experts. Often, Lakhiani interviews his platform's instructors — plus the occasional celebrity or entrepreneur, like billionaire Mark Cuban — to learn their insights on common self-help topics.

His biggest takeaway so far: Dedicate 20 minutes per day to your rate of self-evolution, or "the rate at which you are growing as a human being," Lakhiani tells CNBC Make It.

The lesson comes from Srikumar Rao, an author and the founder of The Rao Institute, a New York-based leadership coaching firm. For roughly three decades, Rao has taught a class called "Creativity and Personal Mastery" at Columbia Business School, London Business School and the Haas Business School at the University of California, Berkeley.

In that class, Rao teaches that the world's most successful people invest a little bit in their personal growth every day.

"More important than 'success' or 'failure' in any endeavor is whether a person grows in the effort," Rao tells CNBC Make It. "Truly successful persons make a conscious, deliberate commitment to personal growth."

The key is to make self-improvement a daily habit, rather than any one-and-done strategy. You might read a few pages of a book, for example, or devote 20 minutes to an online course. You could perform daily meditations or commit to adopting healthier habits, like better sleep or more intense exercises.

Trying to perfectly learn something new in one sitting is a risky proposition: According to the University of Waterloo, most people roughly forget half of anything they've just learned within an hour, unless they implement it immediately.

"Evolving has little to do with learning," Lakhiani says. Rather, he notes, it's about "the layering on of wisdom."

That's why he recommends reading 10 pages of a book per day, instead of devouring it in a single sitting: Eventually, its ideas will begin to build up and become part of your everyday life.

The same tactic applies to any other method of self-improvement, whether you're working on your communication skills or trying to change your personal habits, he says.

"If you invest just 20 minutes a day, you cannot help but become better and better," Lakhaini says.

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