The energy you drew on so extravagantly when you were a kid, the energy you thought would never exhaust itself -- that slipped away somewhere between eighteen and twenty-four, to be replaced by something much duller, something as bogus as a coke high: purpose, maybe, or goals, or whatever rah-rah Junior Chamber of Commerce word you wanted to use. It was no big deal; it didn't go all at once, with a bang. And maybe, Richie thought, that's the scary part. How you don't stop being a kid all at once, with a big explosive bang...The kid in you just leaked out, like the air out of a tire. And one day you looked in the mirror and there was a grownup looking back at you. You could go on wearing bluejeans, you could keep going to Springsteen and Seger concerts, you could dye your hair, but that was a grownup's face in the mirror just the same.

-- Stephen King, "It"