The Cleansing Breath

The Cleansing Breath, as its name indicates, cleans and ventilates the lungs; it also tones up the entire system. You should do the Cleansing Breath at the end of other yoga exercises or just before the final relaxation exercises.
To do the Cleansing Breath, stand straight with feet close together and arms hanging loosely at the sides. Take a deep breath, hold it for a little while, then purse your lips as if you were going to whistle. Now start exhaling forcefully, little by little, but do not blow the air out as if you were blowing out a candle, and do not puff out the cheeks. They should be hollowed.
These successive and forceful exhalations will feel almost like slight coughs which expel the air until the lungs are completely empty. The effort of the exhalation should be felt in the chest and in the back.
Rest for a little while, then repeat. After a week you may repeat this routine several times a day.