Great technique which Mantek Chia explain in his book fusion of eight channels. It helps me in my karate practice. My opponent more grounding than me he have more massive body and he know were is my center and all his strokes have goal to move it. But when I doing this practice he cant move me from my calm:) and its move him from his stable position he trying more and more but his strokes didnt rich target im stay calm and relaxed with inner smile, I find it some fun when your opponent working hard you relaxed and let him go:)