We visited Disney World (in Florida) during 2006 and it was a pleasant experience. I was amazed at the enthusiasm and cheer demonstrated by the performers, especially the "Disney Parade" performers. Those guys perform similar shows and activities daily (twice or more, I believe) but able to keep their enthusiasm and, always, wear a smile.
In IT Industry, I know many complaining about getting bored after an year or two being in the same project. Need to learn from the Disney World performers (that secret !)