I've seen dogs (generally collies) who can hit the deck so fast in obedience videos and the like. How do you teach that? Diesel knows down, he has known that from the very beginning, but he always stretches his front legs out slowly, bum in the air, and then slowly lowers his bum to the ground. This is especially slow if he is distracted by something. He will get slightly faster if we do it a few times. So how do I get that "hit the deck at lightning speed"?