shelby, I LIKE the idea of a REWARD if there are 6-7 x's per week! A movie (Jackie O style sneaking in 100 cal pac popcorns), getting nails done, a massage (these diet books are saying relaxation is key to losing weight), a new book (I'm a geek), etc.
I also like having another calendar for my boy. The x system is simple, but for him, he's three, it'd have to be stickers. Maybe buy some small stickers - then if he helps clean toys he gets one, and each day might be 25 cents or something.