Great question! My DOC is different but I do the same thing. I thought I was the only one, terminally unique, eh, that felt the need to use when I feel good. It's like I just don't know what to do with myself if I am feeling good or happy; I'm much more used to feeling anxious and depressed. So I actually needed to alter those happy feelings to a place that was more familiar to me. It does help to know I'm not the only one.
It's amazing to me that I can get used to being miserable and have that be my comfort zone. I guess it's just going to take practice to learn how to feel okay and comfortable in the times when I feel good. And then learn how to make more of the times when I feel good than when I feel bad. Sometimes happiness is so frightening to me, it's just not a place I've lived in for over 45 years. It'a a long, slow learning process.