DRINKING WATER AND SWALLOWING AIR.
Your body needs a reasonable supply of water and air. Water is used by nature in different ways. Form the habit of drinking pure water from 5 to 8 tumblers a day. Drink slowly and form a mental image of Prana-absorption from the water.
The student needs fresh air too in plenty. If your heart and lungs are in sound condition they will draw in air naturally and extract oxygen in proper quantities. If not, perform the following exercises carefully one by one in the open air every day. They are quite reliable.