I've been away from the forum for a while. We were vacationing down in Puerto Vallarta, Mexico, and I must say that I thought of prostate cancer only a few times during those weeks. Now we're back in northern Illinois and re-adjusting to the snow and cold.
Getting back into a physical fitness regimen is always tough, and while a person can set goals, they're only goals, and we may or may not achieve them, but physical activity usually is a beneficial thing.
I remember some years back when I tried to take up running again after back issues had forced me to give it up. I felt as if I was breezing along at a pretty good clip, only to find that my typical times were not a minute or two slower per mile than when I was younger. I decided walking offered the same benefits with less stress on the joints.
I would say, do what you can and don't worry about what you can't do. We all have our limitations, and an injury caused by over-use can put an end to any fitness program.
I saw a thread when I looked at HW while down in Mexico that talked about why some guys stay with HW and some move away. I've been pretty luck in my cancer "journey" (except for the ED thing, which is beginning to look permanent), but I find I have come to take a real interest in the struggles and successes of all the guys here on the site. We all share certain elements of this battle, and I've gained a lot by taking part here.
I'm sorry you're finding it tough to get back into the rehab program, but I wish you all the best and hope you're able to keep at it and make progress toward feeling better.