I listen to NPR a lot, and recently on the way in to work (my temp work while the museum is closed) I heard a story about a man who plays Santa Claus at this time of year. He said the most important thing, for him is he must believe that he is Santa. Even in the face of teenagers and beard pullers he must believe, once he puts on the suit, that he is Santa.
As someone who spends quite a bit of her time as someone else, often in the face of teenagers and (even worse) retired age men, I must believe that when I am dressed as Mrs. Shapiro and enter museum grounds, I am Mrs. Shapiro. I am in my kitchen preparing meals for my family. When in camp and I get dressed as Hanne Reischach, I am Hanne. On the march in foreign lands with my husband. If I don't believe it, who else will?