We made each of them a little bank (out of fruit snack boxes) covered in Thomas the Train wrapping paper and thier names on them. Every time they are caught doing something GOOD they get a Thomas Dollar. Whatever they earn in Thomas Dollars, we will match at the Toy Tent during the "DOWT" event. So far, I have seen my 4 year-old empty the dishwasher, make his bed and gave me a back rub all for the sake of earning some of these precious greenbacks. Maybe it will work for you?