The following article and practices are directly extracted from “Body Speech and Mind” by Namgyal Rinpoche
This type of breathing is necessary for mastery of Hatha and other yoga practices. These breathing exercises which you are about to learn are excellent for counteracting tendencies to mental illness. Generally speaking, the schizophrenic type doesn’t allow a full expulsion of air.
First is abdominal or belly breathing, second is middle breathing, and third is upper lung breathing. The last part, breathing to the top of the lungs, is particularly useful for counteracting depression.
Practice 1: Belly Breathing
Start this exercise in a standing posture, arms by the sides. Expel all the breath in the lungs, then let the breath flow in to the lower lung area by allowing the belly to expand. Do this to a count of eight.
Practice 2: Middle Breathing
Now for the second part of this exercise, lift the arms from the sides of your body as you inhale, but this time the breath should flow into the middle portion of the lungs, expanding the rub cage.
Again, eight counts breathing in, hold for three counts, and eight counts breathing out.
Practice 3: Upper Lung Breathing
The third part should be done with the feet slightly further apart, the upper chest thrust forward, left hand holding right wrist behind the back. After an exhalation, allow the air to fill the top of the lungs by slowly lifting the shoulders as you inhale to a count of eight. Hold and exhale as before.
Later you can string the three parts together, doing belly breathing to a count of three, middle lung breathing to a count of three, and upper lung breathing to a count of two. Hold and then exhale with the same count. Repeat this process twice more.
Practice 4: De-Armouring
Here is what is called a de-armouring exercise which is very good for Pranayama Breathing.
You need a stool or a low table which can support your weight. Place a cushion on it and then bend backward, resting yourself on the stool so that your waist area – but nearer to the small of your back – is supported. The arms should be outstretched above your head, and the fingertips should just overlap another chair or bench.
Do not hold this posture for more than three minutes. Keep the mouth open while you are doing this.
Lying on your back on a wide mattress and kicking alternately with the two legs is also an excellent de-armouring exercise […]
While you are trying the bending-over-a-stool one, if you have to think of anything, think of your mouth and throat being open. Allowing that area to remain open promotes receptivity.
In pretty well any of the de-armouring exercises it is important to keep the head back and relax the jaw. This happens very naturally when, for example, you experience orgasm during the sexual act. So watch that you don’t have a clenched jaw. Most clinging, in physical terms, can be found in the jaw area. One other minor point (although you don’t have to specifically focus on this) is that it can be helpful to encourage the feet and hands to be loose.