Pranakarshan Kriya

Pranakarshan Kriya (Sanskrit: प्राणकर्षण क्रिया ; Prana=Breath; Karshan=attract; Kriya=action)  (Deep breathing with focussed mind) is done to bring the mind to a focussed state which is essential to do yoga postures and other techniques like Pranayams (breathing techniques). Focussed unwavering mind is a prerequisite for doing yoga postures (asanas) and other techniques.


Verse 2 in Chapter 1 of Pathanjali Yoga Sutra goes like this

yogash chitta vritti nirodhah

Translation : 
Union (integration) of the self to the universal consciousness is the result of restraining fluctuations of the mind.


Yoga = of yoga , union of self to the Supreme or universal consciousness
chitta = conscious thought
vritti = fluctuation in the mind or vagrant thoughts
nirodhah = control, regulation, mastery


Meaning:
The verse beautifully encapsulates in one line, the entire purpose of doing yoga and the way to achieve it.
The mind is pestered with vagrant thoughts. These vagrant thoughts prevents the mind from concentrating. Sometimes new ideas spring from a wavering mind. But if we have a task to complete or a mission to accomplish, the wavering mind needs to be ignored. All yoga postures and techniques need conscious effort to achieve the desired goal. Any posture/technique/action/deed done without conscious effort will not deliver its benefits.
Ok then !! How to achieve a tranquil state of mind before doing yoga ? Doing Pranakarshan Kriya is the way.


Pranakarshan Kriya is done between cleansing techniques (like NetraSnan) and asanas (yoga postures). 


Procedure:
1)Sit in Vajraasan (Sanskrit:वज्रासन ; Vajra=thunderbolt or spine;Aasan=sitting posture; sitting with the spine erect ; the legs folded back from Knees and buttocks rested on the ankles)  and close your eyes.
2)Get rid of the puckers(wrinkles) on your forehead. Tell your mind firmly that you are not going to open the eyes until you are finished with doing all the exercises that you have thought of.
3)Smile gently and feel relaxed.
4)Concentrate and observe your breath for 2 to 3 mins (or until your palpitations subside).
5)Take a deep inhalation and a prolonged exhalation.Try to keep the duration of exhalation longer than that of inhalation.
6)While you inhale, chant "So..." and when you exhale, chant "Hum...". The chanting should be done within the mind.
7)Repeat the cycles of breath for 5 to 10 mins.
8) Now you are ready for performing yogic techniques.