“It is said in the Hatha Yoga Pradipika that the senses are governed by the mind, the mind is governed by the breath, and the breath is governed by the nerves. The yogi learns to use the mind to govern his senses, and he uses his breath to govern the mind. Yet our mind and breath are not always calm and in control. It is the stress that often cuts our breathing short, as our abdomen constricts from anxiousness.
We can not eliminate stress and tension from our lives. Life is of itself stressful. Walking, eating, reading – everything is stressfull. There is nothing in the world free from stress until death. Reather than asking “Can I be completly free from stress?” we must ask, “What is the degree of stress?” What matters ultimately is how stress affects your nervous system.
The main causes of negative stress are anger, fear, speed, greed, unhealthy ambition, and competition, which produce a deleterious effect on the body and mind. When one does good work, it is positive, and it does not cause the far greater stress that comes from grasping and greed.
The parctice of asana and pranayama not only de-stress you, but energize and invigorate the nerves and the mind in order to handle the stress that comes from caprices of life.”
B.K.S: Iyengar: “Light on life”, pg.65-79