0Pranayama is a very subtle practice. It has to be done with focus and awarness to get benefits. There should be no strain in the body or the breathing. The flow of breath should be slow with no breathing sounds, one should be perfectly at ease and acknowledge the MUDRAS consciously during the practice. Kriyas like Jala/Sutra neti will help in cleansing the nostrils for breathing perfectly. ASANA practice also balances and steadies the breathing process. No wonder it is placed after Asanas as the 4th Anga in the Yoga Sutras.
