God shows others himself through how we handle our trials & tribulations. If we do not reflect him through them then we are not showing his life through ours. Be thankful in all things.....even the trials & tribulations......that is one of the ways we show him when it seems our life is no longer worth living.....& it gets us out of feeling that way.....yes, JOB is probably the best example.....but David also fits in there too.
Unfortunately when we get stuck on our disabilities & our PTSD, we are also the only ones that can give us the kick in the rear to live our life for God to shine through the crap. When we focus on how God is shining through us, it helps us put our condition into perspective especially when God gives us that desire to be a witness for his life....even if it's only trough our actions & not out direct words.
We never know who's lives we will touch....& sometimes we never do know who we have touched.....that our attitude toward life is that witness.....sometimes God makes that our purpose whether we like it or not. When it what we knowingly do, then it's easy to get caught up in our own pride.....what "we do" or what "we have done" rather than what "God has done through us". Sometimes unknown to us, that our heart's attitude has really been "what we have done"....remember, God knows our heart even though we may not be willing to admit to what our heart is doing.......God knows what he wants from us & sometimes takes away the things that our heart isn't ok with (& we don't even really know that our heart has been doing that).
I know that my music & my flute playing was a big part what I was doing for God....how in the world could God take away my flute (it was stolen out of my truck 4 years ago & couldn't afford to replace it). I realized that my flute playing was really about me & I wasn't focusing on the God in the whole performance thing I was doing. I do miss my flute & being able to express myself through it.....but that's in my past & some things we just have to accept....not that we feel they are good, but then being thankful in all things is about finding the good in everything that has come into our life as we know that from the bad, God will make good come from it....but we also have to be open to it & be willing to look for that good & see it no matter how subtle it might be. Yes, it can also be looked at as the Polyanna game but the roots of that game came from what God directs us to do with out lives.
Know it's hard to get out of thought processes like this....especially when your neuropathways have had a minimum of 25 years to reprogram....but then it sounds like you were already thinking those thoughts long before your disability hit.....maybe it's God way of trying to wake you up & get rid of that thinking because it's not what he wants from our lives & it's definitely what can be used against us so to keep God from shining through our life.
Keeping you in my

.....& wanting you to know that this topic is something I know God has been wanting me to think about because so much on this subject has been hitting me lately. Just got a new book today to start reading "Radical Together" David Platt. Don't know if you have read it but it's about unleashing the people of God for the purpose of God. Thinking it might be good or discussion in our social group.
What you are going through is something we all go through...you are not alone......the thoughts that I write are just thoughts that have helped me through the same struggles you are having.