Vayu is the Hindu god of wind. Agni is the Hindu god of fire. Both Fire and Wind have transformative attributes. Yet, most people in the West only think of using FIRE (Agni) to make changes within themselves.
What I mean by this is that most people think that they will only see a change in their bodies if they work "harder" in their yoga practice. They think they need a "good workout" - they need to "sweat" - they need to "feel the burn" - Fire - Agni.
However, the changing power of "moving air" - breathing - accessing Vayu - can change the body just as dramatically. In fact, the practice of consciously breathing while performing asanas will calm the mind - thus enabling the brain to emit "relaxation" neuro-peptides throughout the nervous system. This will allow the muscles to relax and open and stretch further than you could by using the burning power of force.
I encourage you to get to know VAYU - the Hindu God of Wind - during your next practice.