What now is Right Attentiveness? […] - Whenever the disciple (a) is conscious in making a long inhalation or exhalation, or (b) in making a short inhalation or exhalation, or c) is training himself to inhale or exhale whilst feeling the whole (breath-) body, or (d) whilst calming down this bodily function (i.e. the breath)-at such a time the disciple is dwelling in contemplation of the body, full of energy, clearly conscious, attentive, after subduing worldly greed and grief. For, inhalation and exhalation I call one amongst the bodily things.

(Buddha Sakyamuni)