If you stand up and lose your posture on the downswing, you're wasting energy that could've been transferred to the ball at impact. This drill will help you get it back.
Take your address with a driver, then extend your left arm and stand up the club, with your left palm over the butt of the grip. Now simulate a swing with your right arm only, pushing down on the driver with your palm as you swing into impact (right). Feel your lower body gathering leverage against the ground as you flex the driver shaft. This is the feeling you want when you make your normal swing.
Essentially, by pushing down into the ground with your lead leg on the downswing, you set up more lower-body thrust for impact. And that translates into more clubhead speed.
Ranked No. 8 on Golf Digest's 50 Greatest Teachers, Rick Smith is based at Treetops Resort near Gaylord, Mich., and Tiburón in Naples, Fla.