There was a study somewhere that regardless of culture or socio-economic situation, people are less happy from their 20s through their 40s, and start to be happier in their 50s and 60s. Also noted is that people in their 50s and 60s, when shown a series of pictures, later tend to remember only the pleasant pictures. The older one gets, the easier it is to forget the bad parts and just focus on the good...
...until your smacked in the face with a teenager in baggy pants that has a hat-wearing disorder screwing up your food because he could care less about you or the work he is doing. Then, EVERYTHING that is current sucks. Everything that sucked about life 20 years ago still remains forgotten, as it is not standing up to smack one in the face.
Not sure if this was the study, but this link sort of describes what I was referring to in the first paragraph:
Since the link is to msnbc, I'll just leave it cold:
http://www.msnbc.msn.com/id/37195913/ns/health-aging/