A brilliant breathing exercise...
I'm not a doctor and am not giving medical advice, but I tried this and felt like I was getting more air.
This is another good breathing exercise.
How To Perform the 4-7-8 Breathing Exercise | Andrew Weil, M.D.
https://www.youtube.com/watch?v=YRPh_GaiL8s
Check comments below the video:
"I have been doing this breathing practice coupled with daily mindfulness practice for several years. Lower blood pressure, much calmer and more clear minded. Just amazing."