The main practice of Zen is awareness of the mind

It is useful to begin with a more tangible object to calm and refine one's awareness. Breath awareness can be perfect for this. We should cultivate a general awareness of the breath coming in and going out. During inhalation, we should simply be aware that this is taking place. During exhalation, we note that the breath is going out. Awareness is allowed to rest calmly in the present, while we breathe in a natural, unforced way.