Hatha yoga is unique for maintaining proper health. But that is only one aspect of hatha yoga. It is also a complete step-by-step system that can take you to the ultimate goal of God-realization and perfection. Therefore do not mistakenly think that hatha yoga is only a physical practice for proper health.

At the inception of your practice, however, you will most likely be relating to hatha yoga for proper health. In that perspective, there are five principles that you should observe:

(i) proper exercise, (ii) proper breathing, (iii) proper relaxation, (iv) proper diet and (v) positive thinking.

Proper Breathing

Next is proper breathing. Why do we say “proper” breathing? People breathe all the time but it is not proper breathing. In fact, it can be very shallow. In order to breathe deeply, you have to expand the diaphragm and intercostals. Yogic breathing employs all those muscles. The more you contract, the more stale air you can expel. Why do you want to breathe properly?

You want to purify the blood and get rid of toxins. When the heart pumps the blood, the blood that comes from the veins carries carbon dioxide and poisonous gases from the cells in the body. The heart pumps the toxic blood to the lungs, giving up all the toxins in the form of carbon dioxide while simultaneously taking in oxygen and prana from the lungs. The heart then pumps the oxygen rich blood throughout the body. So the lungs are one of the most important organs of elimination. That is why you need to breathe all the time. It is not just a matter of taking in oxygen. You need to ventilate the body to maintain balance. You can go to the bathroom once a day but the lungs have to breathe continuously. The more toxic the body is, the more the lungs have to breathe. You will have breathe faster. If your breathing is shallow, it means the lungs are just fluttering and most of the stagnant air is left in the lungs. Just about one tenth of the volume is being exchanged.

Through yogic breathing, you can squeeze out more air and take in more oxygen and fresh air. That is why you feel energized. You feel awake not because of the increased oxygen but because you get rid of toxins from the body. People feel slothful, lethargic and lazy because the body is toxic. The more you can ventilate it and get rid of your toxins, the more alive you will feel. That is why proper breathing is important. And the breathing exercises that we do have a direct influence and impact on the mind. One of the most important things in hatha yoga to remember is the relationship between the breath and the mind. The yogis strive to gain control of the mind by gaining control of the breath. That is of paramount importance. 

When you are stressed and upset, what happens to your breathing? It becomes very quick and shallow. When your mind is calm and peaceful, what happens? Your breath also subsides. It becomes imperceptible and you do not even realize you are breathing. It shows the relationship between the breath, the mind and the emotions. So yoga is really to gain control of the mind. When the mind becomes calm, steady and peaceful, you identify with who you are. This is really the essence of yoga. Everything you do is really to bring the mind to a state of calmness and peacefulness. So this is one of the most important reasons for breathing. It is not simply to just get oxygen and eliminate toxins, but to gain control of the mind. In hatha yoga, you strive to gain control of the mind by controlling the prana. In the beginning, you learn breathing exercises. Later on it becomes pranayama, control of the prana. That takes place through certain breathing exercises. But it is not only breathing exercises that will help you to gain control of the prana. It is your whole consciousness and state of mind. With purity of mind comes control of the prana. 

We also hold our breath at times in the breathing exercises. As discussed earlier, there is always some residual air in the lungs. In kapalabhati you are churning up the lungs, getting rid of stagnant air. You breathe, energize and inhale. Then you hold the breath. By holding the breath, you are stimulating the lungs to function more efficiently. You also gain control of the mind and experience a calming effect during the retention of breath.