Well, last spring I went through 8 weeks of radiation treatment for prostate cancer. Fortunately, we spotted the cancer early enough, and the radiation treatment got rid of it completely with no chemo or surgery. The radiation treatment was basically painless and didn't really affect my ability to work. It took up a lot of time, with the daily treatments, and left me tired overall. But I was able to get in partial work days.
I don't have any personal experience with chemotherapy, fortunately, but several of my close friends have gone through it. That's nasty, and you will feel sick, in bed, unable to do much for some days or weeks. Again, the key is that they found the cancer early enough that you only need lighter doses, not too often.
Now, I'm facing heart surgery in May. They're telling me that I'll be in the hospital for a week, and then recovering at home for about two weeks. They say that during the home recovery, I'll be able to get around and do some things, but I'm just going to be tired and need a lot of rest. After that, they say that my energy will come back, and I'll feel like a much younger man for many more years. It'll be worth it.
Right now, they've got me on some heavy medication which reduces my energy and leaves me tired. I can't lift heavy things or do anything that elevates my blood pressure much. I'm having to learn to be an old man. I don't have any choice. I'm working in my shop, building Scroll Basses, but I'm learning to slow down. Work slowly and thoughtfully, don't push myself, and when I feel like it, take rest breaks. Sit down or lie down for a while. Then get back at it. It's tough to get used to, but I have to admit that I actually am getting work done steadily. Pace myself and keep going. And enjoy the satisfaction of getting the work done.
And that's the most important thing: keeping a positive attitude toward working in the shop. When you are feeling sick or tired from the treatments, keep thinking about how much you enjoy being in your shop and building basses. Don't let the medical stuff make you think that you can't or won't want to go back in your shop. Your goal of beating the disease is to get back there and continue your projects. When you are lying there resting, think about your projects, what to do next, new ideas. Fix in your mind that you are going to get well and get back to your shop soon. That attitude will help you recover.
Don't convince yourself that you won't be able to work again. You will. Don't become afraid to touch your tools, or afraid that you won't enjoy it again. You will.