It's important to remember that even when successful people say things, they're often just opinions, not facts. Starbucks' CEO Howard Schultz once told Jeff Bezos of Amazon, "You have no physical presence. That is going to hold you back." The reality was that not having a physical presence at that time is what propelled Amazon forward.
— (story from The Everything Store: Jeff Bezos and the Age of Amazon)
Everyday we're inundated with "advice": the best way to stay fit, the best way to eat, the best way to achieve a goal, and so on. How much of this "advice" is considered true because someone influential said it and others have just mindlessly propagated it?
Remember to think, question and experiment.