"Make sure your breath is free, moving in and out through the mouth". But what is a free breath and why is it important in Yoga? While teaching as well as practicing, I like to use words to assimilate sensations in the body that would serve the my Yoga practice, and ultimately my life the most. Words like softly strong, easy breath, expansive, melting, knitting, broad, free, simple, long, calm, soft, press, peaceful.....and all these words I would use to describe a "free breath".
As you inhale allow the gradual breath to softly climb up the spine, and the higher it climbs the broader it gets. Picture inside your easy breath touching every surface of the inside of your three dimentional rib cage, and once the breath reaches the shoulders may it only serve to broaden the backs of them as well as the front collar bones. At the top of the inhale, you should be able to pause, not desperately, but integrate the saturation of the experience for a couple of seconds.
As you exhale, gradually and without much momentum, allow the breath to soften your shoulders making the backs of them heavier to the ground, the arm bones get heavy, the chest melts, the front ribs soften towards the spine and keep exhaling until you feel the navel hug towards the spine. Pause at the bottom for two completely empty moments of pure nothingness.
It is from the place of the hugging in to the spine that the new inhale freely rises...and so on.....
It is important to learn to experience this freedom in breath in every Yoga posture that you are in, as well as every transition in Yoga. While you are breathing freely, there is no cagey feeling in the body, meaning that the body is incredibly stable, supported and fluid. Most importantly, this ease of breath means that your nervous system has shifted from survival (sympathetic, stress state) to calm (parasympathetic), and most importantly you are in a healing state.
If ever you get flustered, wobbly, nervous, unsure, too deep and crucially in pain while in Yoga, the first thing your Yoga practice and higher self calls for is to find a free breath.