“Training your non-dominant arm, will teach you fundamentals of geometry and path control that must be mastered to have total control of your swing on the golf course.” – David Lee
When you’re in a normal stance or a weight shift mode you should be able to hit both right and left handers. Spread your feet out, heave it, drop the arm and let the turn sling the arm through. You can hit the ball dead solid in this routing. If you start to mishit shots when you are in a spread footed stance, go back to a cross-footed mode with the left arm until you can hit the ball solidly every time.
If you pull with the left arm while you’re doing this drill, you’ll change plane and miss-hit the golf ball almost every time you swing. If you’re swinging properly, you should be able to hit a soft draw when you’re hitting left handers from a normal stance.