Yoga is essentially based on breathing. Breathing
connects the inner and the outer worlds. It is
connected to energy and thought. The exercises
are deep explorations of the action of the breath.
The practice moves from extensive physicality
to stillness and the reduction of activity to
breathing and through this focus to the restraint
of uncontrolled mental activity and thought.
As a practice in concentration and focus it can
be invaluable for the actor.
One way of looking at this is to consider the
moment after exhalation. Since the intake of
breath is connected to the rising thought this
is a moment where physical and mental activities
are 'in the balance'. In the ninth sutra of the
third part of Patanjali's Yoga Sutras he states:
"To study the silent moments between rising
and restraining subliminal impressions is the
transformation of consciousness towards restraint"