Is your t CBT? I don't think I could do this exercise because for me feelings have to be felt and writing them down analysing them defeats their purpose. This is just my opinion only and if you really struggle with writing the happy thoughts it can highlight just how bad your life is which can make us Anti happy!!!
I really like the others ideas about morning coffee and seeing Gandalf. Now these would make me happy too and excited, do you have anxiety too?
I ask because that inhibits happiness, in gestalt they have a theory that ' anxiety is unsupported excitement' meaning when we feel happy and excited we don't know what to do with it and we worry and it turns into anxiety.
Do you do any body work in your therapy Annie? I think this could really help with your feelings. I still have trouble identifying my feelings but it gets easier. My ex t as bad as she was really good at helping me recognise my feelings. She would give me a menu of possibilities every time I didn't know. I think a lot of us struggle with emotional expression because emotions are not tolerated in some households.