I weigh myself every morning, but I have learned to not let it affect my day. If I'm sticking to my plan and the scale doesn't budge for several days, I actually look forward to the next weigh in. That's because I know when the scale catches up to my healthy behavior it's going to be good number.
I also think of the scale as my body talking back to me. The big loss of the first week of healthy eating and exercise is my body saying, "Finally! Thank you for trying! I'm going to give you an incentive to keep going!" When the scale doesn't move I hear it saying, "I'm just testing your commitment to losing weight. If you pass the test and stick with it, I'll reward you with a nice number in the next few days!" Or it might be saying, "Eat some fiber, girl!" Down a pound in a day, "Thank you for that long walk and good food!" Up a pound, "Just seeing if you were paying attention." Down 2 pounds, "Woo Hoo!" etc.
Now you all think I'm weird, don't you?
I find the first thing I drop from my routine when I'm falling off the wagon is the daily weigh in. It's so much easier to not be accountable when the evidence isn't flashing at you daily from an LCD scale readout.