It is interesting to read all the stories on here, and fortunately it seems most of you are getting out, and like it's been said getting out there is the most important thing, especially when it seems everything is holding you back.
My Dad had prostrate cancer a couple of years ago, the radiotherapy never really effected him much and he'd cycle daily, not far, just to his allotment and back and we'd get out together when we could on the bike, but walk a lot when we couldn't.
Although unfortunately two months ago he was diagnosed with cancer of the voice box (despite not once ever smoking), which has meant major surgery to remove his voice box, Lymph nodes, and a second major op to help things heal in the past month, and eventually attempt to restore some kind of vocal communication as he can't speak now, and I can't lip read well!
The forward plan is to return him riding again at 78, which admittedly there are a few physical obstacles in the way from the second op having to have a muscle taken from his chest which I can see taking a long time to be pain free, but I'm hopeful of getting him back out there on a bike, though it'll be an electric bike from now on I think!