Find a place where you can sit comfortably, undisturbed, for at least 20 minutes. Your back and head need to held straight. You may sit on the floor or in a chair. Your eyes are best closed as you remain still, moving only if it is really necessary. If you must move, notice how and why you are moving.
Simply be mindful of in-and-out breathing. You may feel that your breathing is too short, too long, too gentle or too heavy. Do not try to control it. Stop judging. Just let it be, let it settle by itself as you watch.
It is the process of watching which is the meditation, not what you are watching. Remember not to become identified with, or lost in whatever comes up: thoughts, emotions, judgments, body sensations. When you become distracted, gently refocus your attention on your breathing.
Keep watching. Just breathe...