When I have SOB, I stop do three pursed liked breaths, then in the the nose and out with a relaxing breath. Sometime It take two rounds like that.
It is the method that works best for me. But it comes from CO2 retention and thane my anxiety sighing up my airways. It just takes a few mins to call down and relax my lungs and breathing.
I catch myself holding my breath or humming and not breathing properly. Hope it helps....

Your 02 saturation levels and being sob don't always have a direct relationship. You can be short of breath and your 02 saturation levels may be lower than 88, but you can also be short of breath and have saturation levels well above 95. That has to do with CO2, exertion and the reserve space you have available in your lungs (which for many of us with COPD is pretty small); this means that we can be very sob and still have 02 saturation levels that are very good. If that's the case, you can continue doing whatever you're doing for as long as you can stand it and you won't do yourself any harm.