Hi Tom Jackson,
It is quite difficult to stay optimistic and positive after treatment because of the fear of recurrence. For me, I was not really worried about the relapse but somehow I had severe depression post treatment, which lasted for over six months. I found myself worthless, hopeless and very negative about the future. I didn't feel angry or frightened but I experienced something even worse because I was emotionless, indifferent to things or people around me. Your situation is quite understandable after a fierce battle. I do think you are definitely not alone to feel in this way. If you feel stronger and are back to work, your situation is improving already. Just be patient and open yourself to people around. It takes time to eliminate the negative feelings. People on this forum who have encountered similar mental problem can give you more advice.

Karen