Have you learned “recovery breathing” in PT? It helps me- taking a deep breath in through the nose, exhaling slowly out through the mouth, with lips pursed. The OT told me,” Smell the roses, blow out the candles”.
My understanding is that if you do mouth breathing in and out, or in through the nose and out through an open mouth, the air you are taking in is immediately being expelled, it doesn’t reach down into the lungs for good oxygen exchange in the alveoli, so your body continues to hunger for oxygen and starts you breathing faster, soon panting.
I listen now to my breathing and start the recovery technique if I hear in and out ramping up, old habits stick with you, but this new habit is working for me.

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