Authors:

Eat only when you are hungry. Drink only when you're thirsty. Sleep only when you're tired. Screw only when you're horny.

Al Neuharth (1992). “Confessions of an S.O.B.”, Signet
Eat only when you are hungry. Drink only when you're thirsty. Sleep only when you're tired. Screw only when you're horny.