Aren't your first two sentences internally inconsistent? If you know it felt nice then it seems to me that you remember what it feels like. Maybe your frustration is because you can't chase after it and catch it again, you want that feeling back.

In my experience this is what happiness or other positive emotions are like-- those who study it say that a sustained sense of anything positive (unlike my experience of negative emotions) just doesn't happen. For me, trying to chase after that feeling I want is unlikely to result in feeling it, but if I "wait" for it, trying to focus on the little things that bring me joy-- coffee, having a few minutes of convo with my kid, petting the dog, walking, etc-- it'll come back. I experience happiness more like a visitor where I try to create good conditions in myself for a positive stay, but feel like how it comes and goes is largely out of my control.

I see nothing wrong with fantasizing about no showing on a session-- actually I have no opinion on the "correctness" of no showing in real life. But my logic would be that although there is no guarantee that I'll feel that really nice thing I did in the previous session, if I don't go, there is a guarantee I won't feel it. I guess maybe it partially depends on the kind of risk taking that suits you.