So sorry to hear than you are unable to walk and having back pain. I am always on the go. It's good to get that body moving. I also have a gym membership. See if you can get free transportation with your health insurance. I don’t get this because I work part time. I started physical therapy over 2 weeks now. I try to go twice a week. I want to feel and get better somewhat so low impact workout is good for me.
I also join an online chronic pain support group name mychronicpainteam. This support group helps a whole lot. It sounds like you need to talk to a social worker or therapist for motivational support. Be well!