Energy You Drew On, That's the Scary Part, You Don't Stop Being a Kid All at Once, Richie, It, Stephen King

“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 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, like one of that clown's trick balloons with the Burma-Shave slogans on the sides. 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 blue-jeans, 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. It all happened while you were asleep, maybe, like a visit from a Tooth Fairy.” - Stephen King, It.

Found on Goodreads, at https://www.goodreads.com/quotes/7950136-the-energy-you-drew-on-so-extravagantly-when-you-were.