The process of enlightenment is built into our nervous systems, and it is an automatic process. All we have to do is facilitate it with consistent twice-daily yoga practices, and the nervous system knows what to do.
Sometimes spontaneous movements will happen as the nervous system tells the body some position is needed to help the purification. These movements are called "automatic yoga", and this was probably where all of yoga asanas (postures) came from to begin with. When these movements happen, we just let them, and return to our practices, as they are just more "scenery" along our path.