I'm a recovering thyroid cancer (good cancer) patient. My breathing and immunity had become bad due to my surgeries/treatment but also stress, occasional hookah

I'm a recovering thyroid cancer (good cancer) patient. My breathing and immunity had become bad due to my surgeries/treatment but also stress, occasional hookah smoking, etc. After suffering from severe bronchitis and cough for the first months of this year, I started doing the breathing exercises in this video (https://youtu.be/iUKjuni-6l8?list=PLxdtWIiZAUhoD6mxvZ0gO9ohEQEI9fB5X&t=527 https://youtu.be/iUKjuni-6l8?list=PLxdtWIiZAUhoD6mxvZ0gO9ohE...) regularly (4-6 times a week) based on a HNer's recommendation. All my symptoms have completely disappeared, my breathing has become slower and I have become a much calmer person. My lungs feel really clear. Highly recommend doing these breathing exercises regularly (every day for the first month if possible). This guy, Michael Bijker, also has a lot of good videos on breathing exercises. Here's an example - https://www.youtube.com/watch?v=xBZInO0-ZHk&list=PLxdtWIiZAUhoD6mxvZ0gO9ohEQEI9fB5X&index=2&t=765s https://www.youtube.com/watch?v=xBZInO0-ZHk&list=PLxdtWIiZAU...