1. If it were 100 years ago, we probably wouldn't be looking forward to celebrating turning 40 - we'd be already dead or getting ready to die: the average life expectancy back then was a little over 45.
2. Just when we thought we were totally over the hill, the 80s are cool again - but we know better, having grown up in them, that they weren't cool at all and get to secretly laugh at all the stupid dumb kids who think they were.
3. Somehow it's all okay, because, unlike at 30; no matter how hard you try to make it feel like it matters again, it just doesn't seem important anymore.
4. Our teenage idols [for me: The Cure, Madonna, Nick Cave, The Jesus & Mary Chain, Kate Bush, New Order &c.] will always be and look 10-15 years older than we will.
5. We have now not only total freedom but also the means and experience to do and think whatever we want and not give a shit. No one can tell us what to do. Instead we can look forward to telling others what to do. Remember how restrictive and totally controlled by others life seemed at 15?
6. We got to grow up in & live through what may well yet turn out to have been the most prosperous, peaceful, liberal and technologically advanced period in history. We never wanted or lacked for clothes, food, medicine or stuff; we got to see both the invention and benefit enormously from the dramatic evolution of the home PC and the internet as well as reap the benefits of the social changes of the 60s and 70s that have given us personal and material freedom and access to such a wealth of information at our fingertips that even our parents could but dream of.
7. We don't have to hang out with young people anymore.
8. We're old enough to appreciate vinyl and cassette as more than just a silly fetish or a "coolness" symbol, we can feel genuine nostalgia for them.
9. By the time global warming really kicks in and overpopulation, the end of the oil supply, plus the pressure on scarce resources leads to conflict and misery on a global scale affecting even the first world, we'll either be too old to give a damn or dead.
10. We're the epitome of Generation X. We'll always be cool because we never ever gave a flying fuck in the first place.