I picked up on the this drill at a workshop I attended and Luke Jensen was presenting. He would practice this drill as a kid hours on in with his brother and father. Repetition is king, the 3 Ball Jensen Drill is a great way to learn how to attack and open the court in tennis doubles. It can be a great cardio tennis workout as well. When done 10 times in a row in sequence, your lungs and legs will be BURNING afterwards. Enjoy and good luck! JF