A few suggestions:
1. Increase your airway clearance.
2. Increase your airway clearance.
3. Increase your airway clearance.
No, really, I believe that working on clearing secretions is paramount to increasing lung function and oxygen levels. I have noticed a huge change in my energy, endurance and even quality of sleep since I really amped up my airway clearance. I try to do the Vest 20-90 minutes a day (20-30 minutes, 1-3 times a day), plus Flutter or Acapella. Now, I seem to be able to get stuff out around the clock - and without having to heave and huff so deeply. I've never seen secretions this thick, probably because I've never done so much lung work before.
In addition to Respiratory Therapy, I try to be more active during the day. This is something I've had to work on, day by day. The more I do, the better I feel. I've had a rough few years with more hospitalizations than I usually have and it freaked me out. I'm slowly getting back into purposeful exercise, which just has so many benefits. But if you're starting at a point of low activity due to being sick, you need to take it slowly.
Good luck!!