Once, during the time I was on the faculty of the University of Wisconsin, a colleague in Internal Medicine came to my door to discuss a case with me. He was well-known as a health food nut and obsessive exerciser; regularly jogging up to 50-60 miles a week. While talking to me he started doing pull-ups in my doorway, which prompted me to ask him curiously what he imagined was the point of the continuous exercise and the near-starvation diet. He told me--with no irony or humor whatever--that he intended to "live forever."
Woody Allen once said (and I'm paraphrasing) that he did not intend to achieve immortality through his works; he intended to achieve it by not dying. He, unlike my colleague, was joking. At least, I think he was.
(Note: The cartoon comes from here; and a hat tip to The Corner)
UPDATE: Only the good die young...tyrants seem to live forever.