Alignment is one of the fundamentals of good golf and is an integral part of the mental game. There is simply no excuse for not getting it right. If you are not aligned correctly to your target, it does not matter how good your swing is. If your body is aimed too far right of the target that your eyes see, the upper body swings across the lower body resulting a pull or slice (for a right-hander). The opposite occurs if you are aimed too far to the left of your target.
This tip from Hank Haney gives you a drill to work on while you practice to get you into the habit of being aligned correctly before EVERY shot. This is a key part of any pre-shot routine.