So it seems foolish to think that one can be told how to breathe. Yet, one's breathing becomes modified and restricted in various ways, not just momentarily, but habitually. We develop unhealthy habits without being aware of it. We also live in social conditions that is not good for the health of our respiratory system. As discussed above, scientists have known for a long time that there exists a strong connection between respiration and mental states.
Improper breathing produces diminished mental ability.
The corollary is true also. It is known that mental tensions produce restricted breathing. A normally sedentary person, when confronted with a perplexing problem, tends to lean forward, draw his arms together, and bend his head down. All these body postures results in reduced lung capacity. The more intense the concentration, the more tense the muscles become.