On my clinic blog S.T.C ( www.STCinjury.blogspot.com ) I talk about how doing 3 simple exercises can make a huge difference.
I think this applies especially to CF as when we cough our shoulder will naturally go forward, which overtime can cause posture issues which puts pressure of the rib cage and the expansion of the lungs.
While i was in my hotel room in Oregon I started using my turbo neb as a weight just by messing around. It's not heavy but doing the exercise slowly it will work good enough. So if you don't have access to a gym then use your neb.
I will update this blog on how I have been getting on when I get the time.