Being middle aged I think we have the best of both worlds :) We are young enough to still be vibrant, energetic and want to be out having a good time. Some of us are even healthier than we were in our 20's and of course most of us are wiser (in theory anyway lol)
Young people fear getting older and a lot of it is this media promoted perception that youth is powerful, magical etc. (marketing hype to get young people who don't know any better to spend money they don't have on junk they don't need to impress other people)
Then when we get older the same media turns on us with fear of losing our youth. Suddenly we are bombarded with all the magic lotions, potions and pills to smooth our wrinkles, lose weight, get our "youthful energy" back etc. (more marketing hype to get people our age to buy a bunch of crap we don't need to keep holding on to the illusion of the magic of youth lol)
It's all a gimmick somewhere I'm afraid. All I know is I am healthy, happy and very energetic and will be 40 in October. I eat right, exercise and enjoy life without giving a hoot what others think of me. In my 20's I ate garbage, was quite lazy and overly concerned about doing what society dictated was "right" instead of living my own life. Guess which me I prefer? and I can honestly say I embrace getting older and I am looking forward to grandchildren and retiring (and I plan to do that with enthusiasm too!)
Give me middle age any day! Young people can keep buying into the hype that they're some kind of super special - those of us who are little older know the truth and sooner than they think - those young people will be here too ;).