Cook presents this as his corollary to Steve Jobs' famous 2005 Stanford commencement line: 'Your time is limited, so don't waste it living someone else's life.' Fourteen years later, standing on the same stage, Cook offers the sequel from lived experience. He describes how when Steve got sick, he had hardwired his thinking to the belief that Steve would recover — that he'd still be guiding Apple long after Cook himself was gone. Even when Steve called him to his house and told him otherwise, Cook was convinced he'd at least stay on as chairman. When Steve died, Cook learned the visceral difference between preparation and readiness. It was the loneliest he'd ever felt in his life, by an order of magnitude. The lesson for graduates: when your time comes — and it will — you'll never be ready. But you're not supposed to be.