@lindenflower an inversion board is actually used by people with back problems. But I use it to drain my lungs. Basically, invert myself not totally upside down but at a pretty good angle, and let gravity work. If there's anything to come out after I huff several times, if it comes out then I go upright to spit it out. Then invert, huff a few times, go upright to spin it out. I will do that 2,3,4 times til I feel I've got out everything I can. I don't stay on the inversion more than three or four minutes total. My pulmonologist actually suggested this, and it works very well for me if I can get the mucus loosened. I hope I explain this in a way you could understand. It really makes a big difference with me.