What's the single most important lesson you've learned from playing D&D?
Well, here it is, Day 28 at last, and I've only stumbled once in the home stretch. Now I face the deepest question of the whole challenge, and the most difficult to articulate an answer as well. The short answer is that D&D helped me rediscover my creative side. The long answer requires a little background...
I was not a very outgoing or socially confident kid. I was smart, inquisitive, and artistic, but also quiet and very uncomfortable and uninterested in interacting with people outside my family. I was (and am) on the extreme introvert end of the introversion-extroversion continuum. Had I been allowed to develop at my own pace in all things, I probably would have grown up a lot more secure in my own abilities and personality than I did. But Big Brother doesn't give a flying rat's ass on the lower east side of hell what any particular individual is or is not ready for, and so I was shunted off to the forced indoctrination camp euphemistically known as public school.
I excelled in math and other subjects where there are objectively correct answers. I could come up with them readily, and there was little or no teacher subjectivity involved in grading them. (I may have Charisma 5, but I've got a solid 17 Intelligence.) For a while I did well in the more subjective, artistic fields as well - until they started grading them. If you want to smother a sensitive child's creativity, there's no better way than to make it absolutely clear that his imagination is being judged. It didn't take long before I had no desire whatsoever to share anything I created with anyone else. Get a math problem wrong, and it's the answer itself that's being appraised. Get points marked off a drawing or creative writing assignment, and it's a piece of your inner self that's being judged.
As if that wasn't bad enough, by middle school the English classes consist largely of reading works and then scrutinizing them for all manner of literary techniques and devices, analyzing them for themes and hidden meanings, and generally taking all the fun out of reading. I didn't understand most of it; I could memorize the terms easily enough, but because art is highly subjective, I never really grasped whatever it was these pretentious teachers wanted me to grasp (if they even knew themselves - I'm not entirely convinced that they did.) So, from my point of view, there was some "right" and "wrong" to writing, and I was essentially flying blind because I couldn't tell the difference. Not only was I to be judged on whatever fragments of my "soul" I might jot down on a sheet of notebook paper, I had no clear idea what I could do to weight the scales in my favor. Math and science were a snap; all I had to do was understand and apply clear, logical, and objective principles. Writing was a minefield, and one that ultimately I chose not to negotiate at all. I spent many an hour in class staring at a blank page, knowing that there was absolutely nothing I felt safe handing over to a critical teacher, or worse still, sharing with classmates.
Then I discovered D&D. Those rules, the lists of spells and monsters and magical treasures, struck sparks in my imagination that had been dormant for a long while. I ran the Keep on the Borderlands for my young relatives, but soon I was cobbling together my own dungeons and wilderness areas. It was safe; I didn't have to worry about plot or theme or any of the other literary esoterica over which high school English teachers obsessed. All I had to do was draw maps and write up some interesting things for the players to find in them. I set things in motion, and let the players determine where the story went. They were an easy audience. They weren't there to criticize my creation, nor to pick apart and analyze every detail. They were there to experience it, and to experience the awesomeness of their characters within it, and they did. It wasn't about technical perfection. It wasn't about trying to impress the sensibilities of some inscrutable authority figure in order to earn high marks. It was about fun, pure and simple.
It took me another 15 years or so to really get into writing, and to start to care about all the things that make a story click - stuff that doesn't really belong in a D&D game, because a D&D game is not a novel, but that I would never have cared at all about if not for D&D. I don't think you learn to love writing by learning the "rules." You have to learn to love it for its own sake before you care about style and technique and all that. At least that was true for me. There is something profoundly liberating about creative endeavors for no purpose higher than sheer enjoyment, and that's the lesson I learned from playing Dungeons & Dragons.