At 20, our poor over-achieving and uber-pepped children are still tainted by their immediate adults' high expectations; their psyche is all screwed up by fear of failure, which results in terrible confidence and self-worth issues. No matter what some psychologists say about "infantilism," I firmly believe that these are the main reasons why the majority of the 50 million people in their 20s today appear somewhat stunted in their life cycle. It's our fault.
Far from all, but definitely the best ones, after 5-10 years of struggling through all the psychological and social tribulations their parents, guardians, and the society created for them, come out of it knowing exactly what they want from their lives; acting with more maturity and confidence than any 20-year-old could've possibly mastered, even in "the good old times." (When were they that good for children and young people? I have no fucking clue!) Thus, at its best, the new 30 is something we've never seen before: it is a unique combination of teenage physical youthfulness and adult mental toughness. These 30-year-olds didn't waste their twenties (no matter what the bitter over-the-hill farts say), they used it to get better and free themselves from the bullshit that dragged them back. The ages-old statistical measurements concerning the attainment of stations of life simply don't apply to them, and I can't believe that some esteemed sociologists and psychologists still use them.
This brings us to tennis as a perfect example of this phenomenon. For the first time in the US Open history, three out of four ladies advanced to the semifinals are over 30: Serena Williams (will turn 32 in exactly three weeks), Li Na (31), and Flavia Pennetta (31). If 30-year-old quarter-finalist Daniela Hantuchova overcame Victoria Azarenka (ranked #2 in the world), it would be a 30+ quartet. Azarenka herself, at 24, is not that overwhelmingly young either - she turned pro 10 years ago. And it's not like the three older women played in their "age group" - they went through a bunch of much younger competitors on their way to the semis.
It's remarkable, especially considering that this sport fairly recently saw 16 to 18-year-olds winning multiple Grand Slams in a row (Martina Hingis with a career slam at age 17 in 1997 comes to mind). Now, there is not a single teenager among the top 30 ranked players on both men's and women's sides. Serena Williams after all ups and downs of her, still remarkable, twenties last year won Wimbledon, the US Open, and two Olympic Golds. She played more matches this year than she ever played in her life before (reaching #1 rank) and already pocketed the French Open title.
According to the contemporary medical science, theoretically speaking, these 30-year-young people will have 10 years longer to live than we do. So, if we don't completely destroy the environment, the economy, and the democracy, people in their 30s will have plenty of time to at least try to realize their potentials and can consider their twenties as formative years. If we let them to survive, they will look 35 at 50 and continue rocking on well into their 80s.