To do so, he acknowledges, they may have to become strategically deaf.
"In today's environment, the world is full of cynics and you have to tune them out," says Cook, speaking in Scotland on Wednesday after receiving an honorary degree from The University of Glasgow.
"Because if not, they become a cancer in your mind, in your thinking and you begin thinking that you can't or that life is negative."
Watch the full speech below. (Warning, the video is not of the highest quality.)