From an interview with Harold Bloom:
http://www.theparisreview.org/interviews/2225/the-art-of-criticism-no-1-harold-bloom
Not long ago President Reagan, who should be remembered only for his jokes because his jokes I think are really very good, was asked how it was he could have managed eight years as president and still look so wonderful. Did you see this?
INTERVIEWER
No.
BLOOM
It was in the Times. He said, "Let me tell you the story about the old psychiatrist being admired by a young psychiatrist who asks, 'How come you still look so fresh, so free of anxiety, so little worn by care, when you've spent your entire life sitting as I do every day, getting worn out listening to the miseries of your patients?' To which the older psychiatrist replies, 'It's very simple, young man. I never listen.' "