Your left thumb can create a lot of tension in your wrist, arm, and shoulder. Mike explains how the left thumb has caused many problems in golf. He emphasizes the use of the left thumb is more for support. If you use your thumb to push down on the handle, it can cause tension. In baseball, your thumb isn't extended in the grip. The same is for tennis. The thumb isn't on the back of the racket. Because Mike came from a baseball background, he used that same grip when he began playing golf. When you take your thumb off and make a swing, your arms are relaxed, and it is easy to rehinge the club on the follow-through. As you put your thumb on the shaft, make sure there is no pressure. Don't push down on the shaft with your thumb; this creates tension. On the backswing, your thumb acts as a stabilizer to the shaft. When you swing down to impact, your thumb is loose, and on the follow-through, your thumb stops the club from collapsing at the end. Mike suggests getting your thumb off your grip. Make practice swings to feel how loose your hands, wrists, and shoulders should be. If your thumb comes into play and pushes on the shaft, it will lock your elbow, wrist, and shoulder, making it hard for your hands to work on the follow-through. Again, swing without your thumb on the shaft and switch back to using it without the tension.