When I was going through radiotherapy, most people were managing OK with it. I went out cycling every day which I enjoyed, and I think the exercise probably helps stave off fatigue.
However, there were a couple of guys who were really struggling with it. One of them hadn't even told his wife that he had prostate cancer - I can't imagine what she thought was going on. I made a point of talking with him when we met up in the radiotherapy waiting rooms.