Apple CEO Tim Cook addressed the graduates of the 128th class of Stanford University on Sunday, and borrowed a few words from his mentor Steve Jobs.

"Fourteen years ago," Cook said, "Steve stood on this stage and told your predecessors: 'Your time is limited, so don't waste it living someone else's life.' Here's my corollary: 'Your mentors may leave you prepared, but they can't leave you ready.'"

Cook described the time after Jobs' death as "the loneliest" he'd ever felt in his life, and said he could "sense" the expectations others had for him.

"All I knew," he said, "was that I was going to have to be the best version of myself that I could be. I knew that if you got out of bed every morning and set your watch by what other people expect or demand, it'll drive you crazy."

He urged grads to focus on authenticity and forging something new, rather than imitating others.

"Don't try to emulate the people who came before you to the exclusion of everything else, contorting into a shape that doesn't fit," Cook said. "It takes too much mental effort – effort that should be dedicated to creating and building. You'll waste precious time trying to rewire your every thought, and, in the meantime, you won't be fooling anybody."﻿

Cook had already built an impressive resume in tech prior to joining Apple in 1998, with roles at IBM, Intelligent Electronics and Compaq. But he felt that Jobs had a new and exciting outlook on the tech industry, one he thought he could add value to.