Source: Praana, Pranee, Praanayam:  Exploring the Breath Technology of Kundalini Yoga as Taught by Yogi Bhajan

Here is an excerpt from this book where Siri Singh Sahib Ji speaks about breath:

Breath is life and life is breath. There is no difference between the two.

It is your breath of life. You have to care for it.  We don’t remember that the breath has got any importance for us. We do not know that we are attached to the breath. We think it is automatic and our great grandfather must have signed a lease for it. We worry for everything in this world, but we do not worry on that which gives us life, that is our breath. Moment you don’t breathe, they throw you out. Breath is your everything and you have no time to meditate on that. You meditate on God, but not on the breath, which is the tender charge of God. I have to tell you one thing very clearly. I can only pass on the truth to you. I cannot sit in you and breathe.

Take a conscious breath. Conscious is: take it in as long and deep as you can and take it out as much as you can. That is called conscious breath.” (Conscious breathing is also called “mechanical” breathing.)

What is attractive in you is not you. It is your absolutely radiant body. That is a shining armor around you for protection and attraction both. And (its strength) depends how deeply you consume praana and how many times during the day you try to breathe absolutely mechanically.”

Your mind stops automatically when you are doing a mechanical breath. Your mind cannot go anywhere. It comes right to the point and it says, ‘Yes, master’. Normally it says, ‘Hey, slave, do what I say’. But once you start rhythmic mechanical breathing, mind shall stop. And if you really do it well for a while every day, you will be shocked to find that the mind will not disobey you for any reason.

In yoga never breathe a breath of life automatically, always breathe mechanically. Thirty-one minutes of mechanical breathing can give you better health than you ever had before. It can give you strength beyond understanding. It can give you answers for every question, which you can’t even imagine. Because you live by the breath and you die by the breath. So you must enjoy the breath. And to develop intuition, you must have your breath, the basic elementary power of life, under your control.

Only conscious breathing, praanayam, gives you consciousness. You can breathe automatically. Breathing you can do unconsciously. Why do we do conscious breathing? Are we insane? No. Conscious breathing leaves you with consciousness. Conscious relationship with praana is the conscious relationship with (Divine) Consciousness.

If you do not breathe consciously for eleven minutes a day, you lose 40% of the vitality of life. This 40% you cannot recapture by any medicine or any exercise. But if you do breathe consciously for 11 minutes and make it very long, deep, and slow breathing, that can do exactly what no miracle can do, because our life is based on the breath of life.

Anyone who breathes consciously for two and one-half hours during the 24 hours, which is one-tenth of the day, automatically is given all knowledge, all consciousness, etc. etc. Otherwise you will fight for pennies: ‘Who said what to whom? Why me? Why that? Why? If…But!’

If you can command the breath of life and consciously breathe, you can be in command of your life and environments will relate to you as per your wish.

May we all understand, in the breath of life we can be Infinite and with our fearlessness and character, we can achieve all the riches of the earth to share them with mankind.

Find information about Long Deep Breathing here.