I've been down to 24% and been sent for evaluation for lung transplant, the look on the doctors faces when they would come to talk to me about my status after seeing my results from tests and xrays was my wake up call since then I've gotten up to 40% and am out of the tranplant ramge, and have gained some good solid muscle weight that baffled them my last visit which was 2 years after the one that they were freaking out about. It was alot of hard work, I got into the gym and took up wieght lifting cause I just HATE cardio (yes I know we really need to do cardio) and also was tired of my scrawny body. I was weak as ever, people were looking at me in there as if to say "what the hell is this guy doing! he needs to stay in bed all day and eat lots of ice cream before coming here!" but I didn't care I knew what I had to do. I remember strugling to do just the bar on the bench press so I would use the machines, that was how weak I was! And all through workouts I'd be caughing to bits. Now I am benching 1 1/2 times my body weight on a regular basis, sometimes more! And I have a nice muscular body now, that's the motivation.
And I still belive I can improve more on my lung function cause I'm not very good or consistent with my airway clearance, its just hard to fit everything into one day, I work fulltime and sometimes overtime too, so I'm currently trying to get funding for a vest to help me with the therapy.
Anyway enough rambling from me now, I do believe and have proven that it's possible to improve your lung function, but it's not easy and take takes alot of hard work and discipline.