High five. I'm proud of you for fighting through the pain and taking care of yourself. Maintaining muscle mass does help with chronic issues and you have the right mindset.  I have had shoulder surgery after I literally ripped the front of my joint off, dislocated that same shoulder out the back and ripped it again, snapped my wrist bad enough where it was hanging off my body and they had to plate it back on, and tore the crap out of my knee joint when i wrecked my bike. I go to the gym even though it hurts and sometimes I have to sit in the locker room and try not to cry. Why? If I let myself go, it would only hurt worse.