I've watched a lot of mid-career people, and Yogi Berra says you can observe a lot just by watching. I've concluded that most people enjoy learning and growing. And many are dearly troubled by the self-assessments of mid-career. Such self-assessments are no great problem at your age. You're young and moving up. The drama of your own rise is enough. But when you reach middle age, when your energies aren't what they used to be, then you'll begin to wonder what it all added up to; you'll begin to look for the figure in the carpet of your life. I have some simple advice for you when you begin that process. Don't be too hard on yourself. Look ahead. Someone said that Life is the art of drawing without an eraser. And above all don't imagine that the story is over. Life has a lot of chapters.
-John W. Gardner, Personal Renewal, Delivered to McKinsey & Company, Phoenix, AZ, November 10, 1990