I'm working with a respiratory physiologist in the UK via zoom. There are none here in the states.
She is calling what I have a breathing pattern disorder. I don't hyperventilate too much but I am a "sigh breather". I get air hunger and yawn a lot. Minimal exertion does affect me but I continue to go the gym, mostly strength training with weights, and walk a large dog daily and I recover pretty quickly afterwards.
Okay, what she told me to do is: no chest breathing, only retrain my diaghragm to do the breath. I started by lying down 10 mins twice a day and calmly focusing on the tummy rising and falling. Then I ordered https://chponline.com/collections/respiratory-lung-function/products/powerbreathe%C2%AE-plus-light-resistance?variant=31319419748440 which she referred. It's a training tool that is great! I do 30 reps, twice a day, but try to do more. I bring it with me in my car and do it while at a red light. Also do it standing but it's harder. Still trying! Hope this helps.