I'm not 100% sure why, but I sort of just quit my challenge on Thursday. I think it had to do with several things. Work stress, TOM coming unexpectedly, scale frustration, etc. I haven't gone completely off the rails or anything ... just kind of stopped being uber vigilant.
And you know what? I'm OK with that. I weigh less today than I did the first day of the challenge, and isn't that always the goal??? :)