We have been analyzing Brahman and its cosmology such that we may understand what we are, our life and death, our pleasures and misery, our health, wealth and intellect.  What we have begun to realize that a cosmic resource pervades everywhere and manifests itself as the essence of objects in the universe.  While it gives all objects their features and designs the laws of the universe, it also becomes responsible to give awareness to objects to be able to utilize their features.  This power that makes us see things, hear sounds, feel sensation, taste food, smell odor and use our limbs in motion and work is prANa.  In popular language it's the life force.  

prANa is tacit, latent and is a trigger.  mana is the storehouse, vAk makes us aware of our existence,it's prANa that triggers that awareness.  Like the other two, it's infinite in its scope and operation. It's the most mysterious of the three.  If our knowledge is vAk and what's knowable is in mana, prANa is that enigmatic unknown, which manifests by its own will.  prANa is the cosmic grace to the universe to maintain it, to populate it, to provide mystery to it.  The endowments of prANa are enormous and occasionally look erratic.  Thinkers, poets and scholars in the world have invented techniques to receive grace from prANa, more they know more remains unknown.  prANa makes its plays and we interpret it in our limited manner, as activated by prANa itself.
prANa is infinite, which basically translates that life force is infinite.  We can muster infinite strength by letting our will power rule our life.  The zeal to living is the will power and this zeal is the direct grace of prANa.  While it gives us the strength to cognize, it also gives us our basic life and leaves us when the organs are unable to contain it.  When we excel in anything through single-minded devotion, we have prANa as our support. vAk gets its strength through prANa, mana gets its abode through prANa.  Indeed, prANa is therapeutic, it heals wounds, it cleans mind, it helps our skills gain strength on demand.  In the world religions, it's the manifested God.
In the cosmology of Brahman, prANa is its active agent.  In the terrestrial sense, it's the breath. All objects who can breathe are called prANI, meaning that they are capable of holding the prANa inside them.  It takes efforts to hold the prANa, hence good functioning of our organs is required to have the ability to hold prANa in the body.  Empirical breathing exercises like prANAyAma are prescribed to be practiced regularly in order to keep the body sacs well ventilated to gain energy and activation.  Food is the body of prANa, water is its garment.  It's an old practice to take a small amount of water before and after the intake of food.  It's a hygienic practice.
Poets and thinkers compare fire with vAk, the Sun with mana and the Moon with prANa.  Rituals in religions are hosted connecting the transit of Moon.  The cyclic repetition of moon's phase is connected to the apparent wake and wane of prANa on the earth.  In the famous Gayatri hymn, bhUh connects to the earth, bhuvah to the sky and svah to the heavens, with the corresponding association to vAk, mana and prANa.  Out of the three, prANa is cool, gives the body the security balance and the rest.   It knows the body's intake capacity and provides it as much and as long as the body is capable of handling and retaining it.
Because of its trigger, rise and decay, prANa is associated with the concept of time in the infinite domain of undifferentiated Brahman.  We connect the origin of the universe to a certain time because we think the first manifestation of prANa occurred in the present universe at that time.  In the Brahman cosmology it has no origin and no end.  When prANa resides in a physical body we call it jIva. Cessation of prANa takes us to the state of death, mRta, and the permanence of prAnA is amRta. All grace in life is the shower of amRta, which is the revival and strengthening of prANa.
Conceptually and in the use of language, mana is neuter, vAk is feminine and prANa is masculine. The vedas give the metaphor of mana to a cow, large and big, its expressions as vAk, and its calf as prANa.  A healthy calf nourishes itself with sweet milk from the cow.  In the terrestrial sense, the prANa resides in a healthy mind, nurtured by sweet sounds.  Sweetness of the sound becomes a gauge of prANa and we pray to gain through the grace of Devi.
Happy Dussehra.