Get 2 buckets. One bucket is full of water, the other is not. Pour the bucket full of water to the empty bucket, then get the former empty bucket that now has water, and pour that into the former bucket of water that has no water. Do this with your left hand controlling the base of the bucket and your right hand holding the rim or handle of the bucket. Keep doing this till you feel any tiredness with your left hand. The goal of this exercise is to coordinate your left hand
