Mistakes. Goaltenders find them maddening. They also find them helpful. Notice how they act after giving up a goal. Sure, they react in the ways one would expect. But they also look up at the videoboard to assess what went wrong so they can learn from those miscues.
This is the exact process Edmonton Oilers rookie Stuart Skinner cites when talking about how he's arrived at this stage in his career and his life.
He readily admits he's a product of failure. He doesn't hide from the fact that when he was younger -- a self-described "scrawny kid" -- he couldn't do even 10 pushups and would vomit after doing one set of stairs or most any other physical workout.