Take full swings at anywhere between 0-50% speed.  You can hit balls with this.  Or, you can opt to do it without a ball.  Even more, you can opt to do it by simply hitting a spot on the ground.

The goal is to simply feel your swing at a much slower speed.  Good things--nay, great things happen when we slow down.

The easiest thing we can do is master something at a slow speed then gradually increase the speed.