One of his best rules, arguably his No. 1 for success, may move you farther and faster in life than ever before. But I warn you: It will take some internal work. Because it comes from deep down–from within us all. It’s a rule founded on a very squishy four-letter word that the business world often turns a blind eye to: Love.

Billionaire investor Warren Buffett's recent letter to Berkshire Hathaway shareholders includes some parenting advice based on his own estate planning tactics.