"Deep practice is built on a paradox: Struggling in certain targeted ways operating at the edges of your ability, where you make mistakes makes you smarter. Or, to put it in a slightly different way, experiences where you're forced to slow down, make errors, and correct them- as you would if you were walking up an ice-covered hill, slipping and stumbling as you go, end up making you swift and graceful without you realizing it."
-Daniel Coyle