
Although we cannot control whether or not we breathe, we can control the way that we breathe.
With each inhale we bring oxygen into the body to spark the transformation of nutrients into fuel. Each exhale purges the body of carbon dioxide, a toxic waste. Breathing also affects our state of mind. It can make us excited or calm, tense or relaxed.
What's more, in the yogic tradition, air is the primary source of prana or life force.
Prana is an auto-energizing force which permeates each individual as well as the Universe at all levels - it is the wealth of life.
We may suffer from physical ailments when prana is lacking in the body.
When we are troubled, restless, or confused, we have more prana outside the body than within. When we feel unwell; the quality of prana and its density within the body is reduced.
On the other hand, the more peaceful and well-balanced we are, the less our prana is dispersed outside the body.
Through constant breathing practice (pranayama) we reverse this process, as a change in the breathing pattern influences the mind.
Prana and consciousness (citta) are in constant contact with each other.
Because of this connection between breath and consciousness, yoga has devised pranayama to stabilize energy and awareness.

Yoga Breathing Exercises, which in Sanskrit are called Pranayama, may be done in association with yoga poses or just whilst sitting quietly.
Many people think of Pranayama as just breathing control, but it is very much more.
Ayama means dimension, not control.
So pranayama is practiced in order to expand the dimensions of prana within the body.
The focus of attention is the movement of the breath within, it is therefore very important to keep an alert mind, as the processes that are being observed are very subtle. There is no visible movement of the body as in asana (postures) practice.
It may involve a temporary pause or interval in the movement of the breath.
The act of retaining breath stops nervous impulses in different parts of the body thus harmonising the brain wave patterns.
But the true aim of the various techniques and breath ratios in pranayama is firstly to give us many different possibilities for following the breath.
When we follow the breath, the mind can be brought under control and gain entry into the deeper realms of the mind and consciousness.
Pranayama or breathing technique is very important in yoga. It goes hand in hand with the asana or pose. In the Yoga Sutras, the practices of pranayama and asana are considered to be the highest form of purification and self discipline for the mind and the body, respectively.
Some yoga disciplines more than others (such as Ashtanga) focuses on the flow of breath and the movement (Vinyasa).
The asana practice tells us a lot about our body-mind relationship, just by watching our breath over a certain period through the demands of the postures’
Pranayama techniques involve the use of different ratios between inhalation and exhalation and the duration of the breath retention. The longer the breath is held the greater the gap between nervous impulses and their responses in the brain. When retention is held for a prolonged period, mental agitation is curtailed.
According to yoga we have a fire (agni) in the body, situated in the vicinity of the navel. The flame itself is constantly changing direction: on inhalation the breath moves toward the belly, causing a draft that directs the flame downward like in a fireplace; during exhalation the draft moves the flame in the opposite direction, bringing with it the just-burned waste matter.
It is important in any Pranayama practice that the individual works with a breath ratio that is right for them. This may vary from day to day. If the ratio is too easy the practice maybe becomes mechanical. If it is too hard or complicated there may well be resistance, which can cause problems.
The choice of a suitable breath ratio must take into account two factors, what is possible and what our goals are. What is presently possible depends on how well we can inhale, hold the breath, exhale, and again hold the breath, taking constant care of never forcing to the point of discomfort, gasp or pain.