I think I'd even say that to my child upfront--"You're going to lose. Know that right now. The goal of this game is to do the best you can BEFORE you lose. But you will lose, and that's okay."
Kriston, you describe pretty well the conversation we had for several days prior to the event. I tried to focus on how lucky it was that we'd be able to talk with/learn from some of the best players around, and how we weren't going there to see if we could beat them. This was about learning. The people there were experts, and they WOULD beat ALL of us! We, unexpectedly, ended up having a private hourlong session (DS7, DS5, DH and I) with a young lady who had just placed 6th in an International Women's Competition. I felt like we'd hit the jackpot having access to such a great player, but I could see DS was having a hard time of it. He told me through tears it was hard to feel like he'd played so badly, and he wasn't smart enough to play chess. I think part of it was that she was unimpressed by his skills. There were no accolades for how much he knew or how well he could play. This was new territory for him outside of our home. As hard as I saw it was, I also felt like it was an opportunity to learn that he wouldn't always be the best at everything, but he COULD get better at something hard through hard work. Maybe it was just not the right time, though.
Before he puts his fingers to the keys, we come to a solid agreement about our expectations for the practice. And I would set the bar at "Spectacularly Stinky!" for how I expected the song to sound at the end of practice number one. And with the next practice, we would shoot for "Slightly Less Stinky" and so forth -- keeping some humor in the descriptions and strongly emphasizing that we were not aiming for perfection, only incremental progress.
Dandy, I really like the idea of using humor to get DS to lighten up. I used to do that a lot when he was younger, but somehow we got away from it. Well, maybe I'm the one who needs to lighten up!
And some of you also got me thinking that maybe (as much as he purports to like chess) we need to steer him toward something non-competitive first for him to learn to work through something hard, and keep it separate from the winning/losing issue.
Those of you with kids playing musical instruments.... Did your kids really WANT to learn to play? DS says he'd like to learn piano, but he knows it would mean daily practice and he says he doesn't want to have to do that. Again, with the long school days, I've had mixed feelings about pushing him into more activities that he doesn't really want to do.
Thanks for all the comments, everyone! I really appreciate your help.