After interviewing over 100 successful people, '4-Hour Workweek' author explains how to decide whose advice is worth taking

Tim Ferriss is all about advice.

He's doled it out through bestselling books including "The 4-Hour Workweek" and "Tools of Titans."

And he's been given plenty himself, through his podcast The Tim Ferriss Show, where he interviews high achievers like Marc Andreessen and Tony Robbins.

But how does he decide which advice is good? And you can't take every piece of advice - how are we supposed to know which is worth taking?

At Entrepreneur, Aaron Gell asked Ferriss that exact question.

"Meaningful nitty-gritty advice tends to be situational," Gell points out. "What works wonders for one person might be disastrous for another."

Ferris says the trick is in the testing. "It's only good advice if it lends itself to a good experiment," he told Gell. "And a good experiment is measurable and replicable."

Gell writes:

"[Ferriss] offers an example. We are commonly told to 'Do some exercise in the morning.' To Ferriss, this is bad advice - even if it's a good idea. 'It's super-nebulous,' he explains, and therefore someone attempting to follow this prescription will almost definitely fail. 'It's almost like taking a step in a worse direction.'

"But according to Ferriss, this type of vague advice is what fills most business-oriented books. 'It's like, 'active integrity…'' he says. 'What does that mean? It's like a cheesy motivational poster. Ninety percent of the business-book content out there consists of meaningless platitudes like that.

"But once you define 'good advice' as something you can test, it takes care of itself.'"

Read the full interview at Entrepreneur »