How Letterman knew it was time to go

The announcement, from The Man himself. Letterman calculates that he has done 5,914 shows, 4014 at CBS, 1810 shows at NBC (plus 90 morning shows). He’ll pass six thousand before he exits in 2015. Best line was the one he was giving to the growing number of people who have been asking him when he’ll retire:
“When this show stops being fun, I’ll retire ten years later.”