When I have been discouraged with the on-going quandry of "must move but hurts" dilemma. My physio said that even moving one step is more than not moving at all!
My favourite when feeling poorly is water. After a bad spell, I start with floating! Starts the muscles moving. Then, ever so slowly building up the movement and time. Weight resistance is the goal. Starting with baby steps is still starting!
Strong muscles helps with improving movement, balance and exercise tolerance. Then adding on slowly as I 'progress'. If I jump in with an overly ambitious effort, then it all crashes, and end up more discouraged. ( the nursery story of the tortoise and the hare comes to mind!)
Have you tried starting with one pound weights or even 1/2 pound?
"Any movement is better than none".
I understand how Osteoporosis feels like such a threat to our future wellness.
Sending you a big hug ! All the best!