When I was working at Mad Genius, a local ad agency, I was a decent “interactive designer” but something I struggled with was asynchronous JavaScript. I just didn't understand it at all.
One of the senior devs helped me one day, stood at my desk for like 15 minutes and explained jQuery’s deferred objects to me in a way that finally made it click (of course that translated to Promises easily enough).
There’s not a point to this story. I just feel appreciative.