Breathing is a change of shape
Air moves because the container changes. Start there.
Describe an inhale and an exhale as changes in the shape of the torso.
Instead of thinking of breath as air arriving, think of the thoracic and abdominal cavities changing shape and the air following. When the shape can change easily, the breath is easy.
When a posture limits the shape change, the breath adapts rather than fails. This is why the same person breathes differently in a fold than in a backbend.
Breathing changes torso shape
The torso can change in more than one direction during a breath.
This is a simplified learning diagram. It is not a reviewed anatomical illustration.
Child's Pose
Open Child Pose, then Cobra. For each, say out loud where the torso can change shape and where it cannot.
Sit comfortably and let your chest drop toward your belly.
Notice: Notice what happens at the back of your neck and in your lower back, and notice that the movement tends to draw out an exhale.
This is noticing, not instruction. Move as little as you like, stop at any point, and watching instead of moving is a complete way to take part.
Can you explain a breath change by naming what is limiting the shape?
Pause before opening Practice. Say the distinction in your own words.
Where is the room for this breath, and where has the room gone?
Breath material is study language, not breathing instruction or therapy. Do not prescribe breath holds, retention or bandha practice; a teacher in the room is the right place for that.