Prana
The yogis want us to control the physical prana in order to awaken the psychic prana.

There is no greater addiction in all the worlds than prana; life.  It is a huge benefit if one can get it under one's control.  Otherwise, there is constant transmigration.

The yogis do not start with controlling the senses.  That is nearly impossible.  They seek to control the power of the senses, prana.  The senses are alive with prana.  This is why they are so addictive.  We want to see everything, hear everything, and when we do not we get frustrated.  The sense of seeing is not the eyeball.  That is only the external apparatus.  Meditate, then, on the power of the eye to see, and reach deeper understanding.

Swami Vivekananda writes in the "Song of the Sannyasin," "This thirst for life forever quench."  This thirst for life is prana.  This is the source of all addictions — coffee, drugs, adventure, travel, experiences of all kinds.  And it is all centered at the manipura chakra, wherein countless nadis (subtle nerves) enter in and out, and through which transmigrating souls (ancestors) enter and exit human embodiment.  Getting over the addiction to prana, life force, means mastering the prana.  Then one can ride it like the Garuda Bird of Lord Vishnu.

Before one can fully recognize Shakti and Kundalini, one will have to recognize It in more basic things.  What is the reason for the flow of events?  Is it coincidence? Luck? Good fortune? Dharma?  Svadharma?  Svadharma, one's highest destiny, is the true intent of all things.

If one does not gain control of one's prana before death, it will be out of control during and after the dying process.  Unconscious death and a random rebirth will be the result.

When prana is sluggish, that is tamas; when out of control, it is rajas.

Whether one is in bondage or freedom, this prana is very important to control.