Two very successful psychoanalysts occupied offices in the same building. 
One was 40 years old, the other over 70. They rode on the elevator 
together at the end of an unbearable hot, sticky day. The younger man was 
completely done in, and he noted with some resentment that his senior was 
fresh as a daisy. "I don't understand," he marveled, "how you can listen 
to drooling patients from morning till night on a day like this and still 
look so spry and unbothered when it's over."
The older analyst said simply, "Who listens?"