Whether you're old or young, you always wish you were 21. Old enough to have responsibility, young enough to have a lifetime of choice in front of you.
I disagree about there being an ideal age (or, at least that it's 21 -- I'm not quite old enough to make a universal comment!).
Are there great things about being young (whether that be 16 or 21)? Sure. But there are a lot of great things about being older too, and it's easy to lose site of those things. I'm 30 now and I'm much more comfortable in my own skin now than I was even 5 or 10 years ago. Generally, I'm happier now than I was back then. I'm definitely smarter and more capable, in work and in life.
It's easy to think about how great it would be if you could be 21 again (while still knowing everything you've learned from your experiences since then), but, as they say, youth is wasted on the young. That's just how life works.
All we can do is encourage people of all ages to make the most of the opportunities they have right now.
