It is indeed not the most active Yoga class. It is more of a healing Yoga class that is very good for you. During class you do exercises that give your body a rest. Consider, for example, that the exercises are held for longer, which are not particularly strenuous. You do many exercises lying down, although there are also sitting postures. It is also important to focus on your breathing during Restorative Hatha Yoga, so that you actually pursue a form of meditation.