Lori - you just go ahead and borrow whatever you like
As for a challenge, I don't know. I know they work for a lot of people, but I don't do good with them - especially when it comes to a scale game. I tend to fall short and then I beat myself up. Now that I'm almost to where I think I want to be, I far more focused on eating right and exercising.
Maybe it should be more along those lines? Like a weekly challenge to get X many minutes of exercise in X times a week? Something that reinforces establishing the healthy habits we'll need to maintain our new selves.