On Wall Street, the saying goes, lucky is better than smart. But after messing up royally and losing all his client’s money and his business to an arrogant bet in 1982, billionaire investor Ray Dalio was determined to learn from his mistakes and create his own luck through smarter, “believability-weighted” decisions. $160 billion in managed assets later, it’s safe to say his method for doing this — developed at Bridgewater Associates, his hedge fund in Westport, Connecticut and set forth in a new 569-page primer, Principles—is compelling. And it’s not just for financiers. I’ve found myself applying a few of his basic, but easy to neglect techniques frequently since reading the book. For example, when something doesn’t go my way, I actually write down what I’d do differently next time. For Men’s Health, I asked him about some of his more controversial practices, and his passion for diving deep beneath the waves. Naturally, he previewed the book in a TED talk, found here.