My Bradley gunner in Korea was a scratch golfer and got a full scholarship to Kansas. He was the kind of guy that was just naturally gifted at EVERYTHING... except discipline. The reason he was in the Army is because when he got to Kansas, "swinging the club"/golf became, "Today, you are going to hit 5,000 balls with the 5 iron." Couldn't do it, lost his scholarship. I think like most sports, it's that combination of a natural gift PLUS discipline that makes the difference.
Follow-up: the guy is still incredibly talented. After he got out of the Army, he worked as a golf pro, started a band (could play anything AND sing... he totally blew away a USO touring band in Korea by getting up on stage and playing harmonica to their songs without knowing any of their songs), was a gifted writer, and is now a legitimate screenwriter.