Very few people breathe correctly. Some use only the upper part of their lungs; others breathe with only the diaphragm (lower part) leaving the upper structures of the lungs inactive and partially collapsed. In those parts of the lung that are not used, slimy secretions accumulate and the tissues become devitalized. Thus a luxurious soil is prepared for the tubercle bacillus, pneumococcus and other scavenger germs. This habit of shallow breathing accounts in a good measure for the fact that one third of all deaths result from diseases of the lungs. For one individual perishing from food starvation, thousands are dying from oxygen starvation.
Breathing problems can be corrected by yoga through the practice of Pranayama. Pranayama has various techniques that are designed for the maximum capacity utilization of the lungs - something that most of us do not do. Yoga and pranayama also help in regulating the temperature of the breath flow thereby solving a lot of problems related to breathing.
The effectiveness of breathing exercises depends upon the mental attitude during the time of practice. Each motion should be accompanied by a conscious effort to make it produce a certain result. Much more can be accomplished through mental concentration by keeping your mind on what you are doing than by performing exercises in an indifferent, aimless way. Yoga and meditation exercises specifically provide such a training.
Do not breathe through the mouth. Nature intends that outer air must reach the lungs by way of the nose whose membranes are lined with tiny hairs and mucous which serve as wonderful filters. Also the air is warmed and moistened before it reaches the lungs which is extremely important. Jalaneti is highly recommended by experts as a way of keeping your nasal passages clean and clear.