About two years ago I was doing a clinic with Lee Trevino and Chi Chi Rodriguez, two of the greatest shotmakers of all time. The discussion turned to controlling the trajectory of your shots. Lee demonstrated a drill he discovered growing up in Texas, where you want to keep the ball low under the wind. He showed us how he developed control of the clubhead through impact by practicing low-trajectory shots with only his left hand on the club. (As a kid, he'd do this while he rounded up practice balls, knocking them to a central location.) The drill encouraged him to use and strengthen his left arm and wrist for crisp iron shots.
Try it yourself. Grip a sand wedge or lob wedge with your left hand only, and position a ball in the middle of your stance. Place your weight fractionally on your left side. Swing the club back so your left arm is close to 9 o'clock. Then swing the club down into the back of the ball. The ground will limit your follow-through. Think hit and hold.
This drill trains the left forearm to identify the feel of the handle staying ahead of the clubhead through impact.
It teaches you to make proper divots with your irons and results in a powerful, controlled ball flight. Alternate hitting one-armed shots with your normal ball striking.
FLICK, a longtime Golf Digest Teaching Professional and PGA Golf Professional Hall of Famer, worked with hundreds of amateurs and tour players including Jack Nicklaus.