The younger you are, the more alive you are. You should aim to be as young as possible. I was at dinner with my family just earlier tonight, and my uncle was irritable that "this kid" offered him his seat, because there were plenty of people older than him on the C-train. I'm sure he wasn't irritable their, but everyone hates aging. Those who age the least are the the greatest. Ultimately, age is a state of mind. I intend to still have golden (people who say "blond" are jealous) hair into my 50's. My dad had golden hair into his early 40's so I intend to beat him by a decade. You have to set goals like this. I could go on about the attributes of youth I intend to keep, but I won't.
Just remember that "age" is simply a construct of society that was created by people who are probably less intelligent than you because they need to be able to grasp things physically in order to be happy, so they attach personality windows onto ages. If you go out of these windows, you are not "acting your age" whether older or younger. Just fuck the whole thing. You should try to be as young as you can. The way you now you are truly a man of youth is when you get angry when people treat you like you're old, as did my uncle. Keep the fire of youth in you.