A very simple but important drill. When we become afraid or startled we tend to bring back the neck inside like a turtle. To become aware and to clean this tension out so we can move freely as a whole lie on your back with your legs extended and together. Slowly bring all the parts of your back to the ground until you are touching it without tension using all of your back and do not advance until you can do this drill with the neck relaxed and the head free to move and the breath unchanged. Once this is done (it can take more than a few tries over a while) slowly lift your legs off the ground together and again keep the neck relaxed and the breath free. Once again this is done lift the legs overhead and back while at all times keeping the neck relaxed and free.
If you do the drill with no meaning to it than you are less than effective. Effort without intent is a dead end.