We have a saying at our house: You are the KING of you! We usually teach this at family night, with fake crowns, the idea being to teach the concept that each child can control his or her own body. They are in charge of every decision they make. And they need to be responsible for those choices.
We usually do some role plays along with this, showing how they can be the "king" or "queen" of their own selves in any situation, even if they are confronted with temptation. Because we do this, we are then able to say "Who is the king of you?" when they try to say things like, "It wasn't my fault!"
This imagery really works with young children, and I even remind my teens of it sometimes. Children WANT to be kings and in charge of SOMETHING. So they really like to think of it that way. Usually after we remind them that they are kings, they use self-control better and try hard to do what is right.
Hope this helps your children as much as it does mine!