Breath is a constantly cycle that keeps us alive and is entirely connected to our emotions, or state of mind and our soul. This is not a religious or mystical approach, It is more spiritual and a bit of etymology can explain that.
In Portuguese, the words inspiração (inspiration) and expiração (expiration) are used to refer to the breathing action of inhale and exhale respectively. The word inspiration has the usual meanings of new ideas and creative enthusiasm, while expiration indicates the end of a certain period of time.
Both inspiration and expiration originate from the Latin word spirare, meaning breathe, with the prefixes in- and ex- specifying the particular action of breathing. Both are related to spirit, or spiritual, from Latin spiritus, meaning breath or vital principle of the individual.
Knowing this, I invite you to inhale, exhale and through Yoga connect to your inner self and find your inspiration and accept the expiration.