Peter,
Glad to hear that the treatment is progressing. The chemo and radiation is no walk in the park but should get the job done. You already know to keep your hydration and nutrition up - so that's good. If you can to a bit of a walk every day it will help keep you spirits up - I am convinced that our daily walk with our old dog did my husband a loo of good.
As the radiation hits, you will not have as much energy as you think you should. Be gentle with yourself and get your rest, too!
Best wishes to you and Deb!
Maria