Tasmin sati Shvaasa-prashvaasayor gati-vicchedah praanaayaamah
When this is achieved (perfection of posture), next is regulation of the breath which is the interruption of the flow of the inhalation and exhalation.
First we must contain our animal nature by stopping the urge for constant physical movement (offshoot of the evolutionary quirk of ‘eat or be eaten’ therefore do not stay in the same spot for too long otherwise you may miss on opportunities or yourself be eaten). Be Here Now implies first to take stock of our physical presence in our current environment in this point in time. Then we can coax our physiology that everything is ok and is going to be ok by being physically still and relaxing, letting go and melting into our given posture or Asana.
Now that we have calmed and stabilized our physical self, the next stage is to stabilize or regulate our breath, in other words our internal vitality. Breath is life and life is breath, and there is a very strong correlation between the activity and quality of the breath and mind. When the mind suffers a panic attack, the breath becomes shallow, rapid and erratic (over active sympathetic nervous system response). When one is in a very relaxed state, the breath is deep, slow and hardly perceptible (parasympathetic nervous system response). The breath is the easiest and most direct of all autonomic processes to control and influence. This is done by the regulation of the breath which is effected by interrupting the flow of the inhalation and exhalation. By consciously regulating the breath we can thereby impact on the modifications of the mind to enhance its stabilization so we can go deeper into the exploration of Consciousness itself.
This is also good methodology for maintaining composure when facing the trials and tribulations of daily life. Either at the onset of mind experiencing cogitation, agitation, perturbation or when about to react to the words and actions of others, where and when appropriate stop whatever you are doing and pause. Be still and become aware and present of your physical self. Then observe (focus on) and consciously slow down your breath. The urge to emotionally react has now somewhat if not altogether dissipated. You are now in a better state to appropriately respond to the situation. Congratulations you have performed the first two and most important steps in managing your states. In fact this is your ticket to living life by design rather than by default. In other words, the path to self-mastery.