Management — that is, placing the ball in the right position for the next shot, knowing exactly where to be on the green — is eighty percent of winning golf.

Ben Hogan (1912-1957) American golfer

(Attributed)

Longest form of this widely attributed phrase found.  Many shorter paraphrases are quoted instead, most commonly "Placing the ball in the right position for the next shot is eighty percent of winning golf."