Long backswings are all the rage in golf these days, and for good reason. Long backswings can help you generate more speed, which help you hit the ball further, look cool, and shoot lower scores.

Except like everything in golf, it’s not quite that simple. You can’t just go swinging as far back as you can and automatically expect good results. Your goal may be to lengthen your golf swing, sure, but in reality it should be having the flexibility to actually do so. If you don’t you may be falling into the trap of “overturning”.

“A lot of golfers making these huge, crazy overturns, sometimes to the point where they lose sight of the golf ball,” he says.

Some people can get away with this, but for most of the rest of us, overturning to an extent like this will cause golfers to lift out of their posture on the backswing and collapse their arms. The combination of these things can cost you consistency and perhaps even risk injury.

When he sees a student overturning, Webb turns to something called the pen drill. It’s simple enough to try yourself: He’ll give students a pen to hold in their mouth with a simple directive: Turn as much as you can, but make sure that by the top of the backswing, the pen is pointing no more than a foot or so behind the golf ball.

“If you do that, you’ll have the right amount of turn, and hit more solid shots because of it,” he says.