Breath depth teaches us how to allow the relative intensity of the effort to determine the depth of the breath (as well as to experience the passive inhalation in controlled settings). It relates to three of the four types of breath volume in our lungs: + Normal breath: The volume of our normal exhale/inhale + Complementary breath: The volume above our normal breath requiring moderate effort to exhale + Supplementary breath: The volume above our normal breath requiring intense effort to exhale + Residual breath: The volume of breath remaining in our lungs above maximal exhalation If we’re alive, then residual breath is not an issue. We only need to consider normal, complementary, and supplementary breath. In yoga, these relate directly to skin, muscle, and organ, respectively. The more challenging the pose, the more we must exhale into the challenge. At first, we can only exhale just off the top of our lungs at a clavicular level – the challenge is so great, the fear reactivity so strong, the myofascial density so thick, the residual tension so tight, the sensory motor amnesia so blind. But over time we relearn the ability to exhale more deeply from the normal breath to the complementary depth into our intercostals. And with protracted practice, we learn to get deeply to a diaphragmatic level through exhaling our supplementary breath depth. With each of the three volumes of air expelled, we become increasingly more stabilized and able to release deeper and deeper bound structures.