"Anhedonia." There's a new word.
I completely understand what you seem to be saying. Ecstatic, exuberant joy isn't something I feel often, and I prefer to keep my excitement a bit understated. I prefer the calm, content sort of happiness over the extroverted enthusiasm one sees portrayed in film and TV.
It's probably a combination of nurture and nature. As a Minnesotan, this highly educational PBS feature explains a lot about the culture where I grew up.
Enjoyed that. Very Scandinavian, in a way... which figures, since so many people of Nordic extraction settled in Minnesota and Wisconsin.
There's just not a lot of exuberant expression in Scandinavia, and I do remember some of the louder and more enthusiastic kids being told to "tone it down."