Bill Walsh might have said it also, but this football coach was probably first:

"Bull Cyclone once said to Tommy Atkins, a player who became a career Marine, 'Tommy, there are two kinds of young men—those you have to kick in the pants to get their potential and those you have to pat on the back. If you, as a leader, make a mistake, you've done a great injustice. So be very careful and decide as accurately as you can whether to kick or to pat.'"

See http://sportsillustrated.cnn.com/vault/article/magazine/MAG1...