When you're swinging a short iron, you can stay fairly centered over the ball and hit solid shots consistently (top, right). But for a long iron, hybrid or wood—when you're looking for distance—you've got to get your upper body behind the ball (top, left). You should feel as if you're loading your weight into your right side, with your spine positioned behind the ball.
Think of the short-iron swing arc as shaped like a teacup. As a result of the club's upright design, it's a more vertical shape. This promotes a descending delivery into the back of the ball so the club pinches it off the turf. But when you swing a longer club, you should think of the arc as wider and shaped more like the saucer under the teacup. You need to be making more of a sweeping arc, particularly with the driver. Loading into your right side helps you accommodate the wider arc, and you'll hit longer, straighter shots.
Based at ChampionsGate near Orlando, Leadbetter runs 30 academies worldwide.