About a billion heartbeats

(from John Sharp's blog):
Many years ago, astronaut-legend Neil Armstrong sat down for an interview with news-legend Walter Cronkite. It was just after the time of the Apollo project, which was coincident with the beginning of the jogging craze.

Cronkite asked Armstrong for his opinion on jogging. Armstrong thought about it for a second, then responded:

"I believe that the Good Lord gave us a finite number of heartbeats and I'm damned if I'm going to use up mine running up and down a street."