This is pretty obvious, but we saw it in practice again this weekend. The wackiness of the weather had D in quite a funk; but with my mom's help, we played silly games, and D's mood slowly shifted until he was giggling and laughing -- and like that, the funk was gone.
We've noticed often that if we can just get him laughing (like tickling, if necessary), he'll be able to push aside the other stuff and be okay.
I like the 'liberating' part of this too...I often forget that, but laughing truly is freeing. Have you noticed that?