”Breathing in, I know I am breathing in. Breathing out, I know I am breathing out." After saying these sentences, we can abbreviate them by saying "In" as we breathe in, and "Out" as we breathe out. We don't try to control our breathing. Whether our in-breath is long or short, deep or shallow, we just breathe naturally and shine the light of mindfulness on it.
A steady, controlled breathing rhythm over a sustained period can have a calming, centring, and energizing effect for the breather.
This style of breathing exercise has been practised for centuries by shamans, meditators and layperson alike.