Breathing is the most important thing any living creature can do. In human beings it the direct connection between mind and body. By controlling the breath, a person can alter their emotional state. In meditation, some people focus on their breath as a way of distracting their mind.
There are various breathing techniques and exercises which can improve lung capacity and health. Breathing should always be done through the nose and start in the stomach, the diaphragm. There are also techniques to help people relax and fall asleep more easily and quickly.
Yoga practice are about breathing as focusing on the breathing a method of meditation. Right breathing is also important for brain health. The human brain requires a lot of oxygen as does the rest of the bodily functions.