While most golfers certainly understand that the body supplies the motive power that their hands actually release, few of them seem to have a clear picture in their minds of what correct, balanced body action looks like—or feels like. In their misdirected efforts to get some power into the swing via the body, 95 out of 100 players sway as they take the club back. That is, they move the bulk of their weight to the right in such a way that they push themselves off balance immediately. That sway finishes the chance there and then for a correct swing and a good shot. The rest of the swing is a rushed attempt to compensate for that first big error.
The best image, I think, for conveying the nonsway pivot (which sets up the desired exchange of weight) is the one Percy Boomer introduced years ago. His advice—and I endorse it heartily—is for the player to imagine that he is standing inside a barrel about as wide as his stance. Then the player must feel as he swings that he is turning inside that barrel, turning freely but without touching the right side of the barrel going back or the left side following through or, for that matter, any side of the barrel. This is the introductory step in getting the right concept of rotation.
from BILL ZONKER, Seattle Golf Club, Seattle, Wash.