My sister is adorable. Tomorrow she finds out whether she passed the bar exam, and do you know what she and her husband are going to do if she passes? Decorate for Christmas! Isn't that a fun celebratory activity?
I was thinking too, that you if have a child in sports right now maybe you could do something similar. Say if your daughter is on the volleyball team- the next time she has a game, you could tell her that if she wins, the family will decorate for Christmas. Maybe her whole team could come over to help! If they lose- oh well, just say it again the next time there is a game. Hopefully she'll win some time between now and Christmas! :-)
(Of course, you'd have to gauge your own child and know whether it would be fun or just add unneeded pressure.)