Saw something on Reddit a while back concerning maturity. Basically when some guy was younger he saw 25+ people as mature and grown up and, believed when he was that age he'd be the same. But when he hit 25 or so he felt no different and wondered why.
He asked his dad who said something along the lines of, 'No one ever grows up, you just learn when and where it's required of you to appear mature.' Similar to that anyway.