This episode goes further into the 4th limb of Yoga- Pranayama. 
Prolonging the life force and quieting the mind as a preparation for the last four limbs of Yoga is the goal of Pranayama. 
In Yoga and in TCM, there is a mention of Prana or Chi also known as life force. This is the energy field that is within and without, inside and outside this body.
We derive prana from the Universe when we inhale the oxygen and this life force is necessary for our cellular system. Pranayama consists of breathing practices to enhance the life force in order to enhance life/ longevity. 
Listen to this week's episode to learn more.