When former NBA star Shaquille O'Neal chooses which companies to invest in, he follows one rule: "I'm going to invest in things that are going to change people's lives," he tells CNBC's Bob Pisani at BITG's Charity Day, adding, "my style is very simple."

He's not focused on crunching numbers: "I never say, 'If I invest in this, five years down the line, we could sell it for this.' Every time I've had that model, it's always been a failure."

His method has worked out so far.

Since retiring from his 19-year basketball career in 2011, O'Neal has seen just as much success off the court. He has invested in Google and Apple and has since accumulated an impressive portfolio. He has embarked on a number of business ventures, owning restaurants and fitness centers and opening night clubs, and most recently, he has become the style ambassador for JCPenney's "Big & Tall" business.