That book is on my "to read" list! After reading your post I'm going to move it up on the list. I think being happy depends, if the parents prioritize it as something important then the kids most likely will too, and that's what I try to do.
There are definitely cultural differences at play in our household. As a Brit, I'm probably guilty of seeing the glass half empty, whereas my American husband is much more of a Pollyanna - if you know what I mean. Sometimes I wish Americans wouldn't be so optimistic all the time because little kids in particular, have a really hard time dealing with disappointment.