There were several times I was probably peak happy in anticipation of a reward, but then didn't enjoy the reward nearly as much as the anticipation.

Biochemically, probably the first time I took MDMA. I literally said, "oh this must be what being happy feels like." (I've only done it thrice otherwise and one microdose ... and was disappointed ... first time was exploratory ... other times felt too recreational ... I don't want to get high ... I want to get better generically.)