I think......

I can understand the frustration. At 47 I am still in good shape but I still get a random back strain 1 to 2 times a year. Each time, It seems like a window to my future where I am unable to be limber enough to bend, stoop, crouch and roll around under these cars. It is actually both scary and sad for me to think of.
I read here the 30+ responses from people that know and appreciate your efforts. I wish you luck in whatever you choose. Years ago Anthony Hopkins declared that he was through with acting and was calling it quits. It turned out he was simply going through some personal issues and he worked them out. Sorta apples and oranges, but even the greats have to deal with adversity. I'm sure you are strong enough to keep the fight.