My 20s were lost completely to a black hole of depression, from which I only started emerging in my early 30s, a dented shell of a human being with little life experience. I've just turned 44, have a wife and child, but still have a long way to go in terms of forming, not helped by poor life choices and multiple health problems.
Aging was always terrifying, particularly when in my mid-30s I'd realized how much I'd actually lost, I've come to terms with that now but need to re-focus on my health (quickly) and improve my lifestyle while continuing to adult better and faster.
In relation to aging, which in effect is just time, I'd suggest the following:
1) Live full, long days. Don't run yourself into the floor but try and finish the day in a better position than you started it, get something done.
2) Try new things/media to stay at least slightly in the loop, but accept that what you like is largely 'set' now. In gaming terms this means not trying to force yourself to play RTS games when you just want to shoot things.
3) Also in gaming/entertainment, recognize what you used to like as opposed to what you actually enjoy when left to your own devices.
4) Do what you always told your parents etc., which they didn't want to, look after yourself!
5) If something's not happening, whether it's playing a particular game, decorating a room in a particular way, going to this or that destination etc. recognize it sooner and stop investing time and money in stuff that's not going to bear fruit.