Start on the ground with your hands planted and step back into push up position. I demonstrate 3 different ways to do this move. The key is bringing your knee as far up and close to your chest as possible. In one way, what I call Slow Mountain Climbers, you can tap your foot down in the middle and repeat on the other leg. The other is to simply bring one knee up and return it back in a marching motion. The last is to "run" in a marching motion.