Completely?

I am working on preparing a lesson to teach at the After School Club this afternoon. It is from I Samuel 12-15, and is about how Saul was instructed by God to kill all the Amalakites and their livestock, but instead kept the best for himself. He did not obey completely. That is the point of the lesson - complete obedience.
Last week we taught about giving God first place in your life.
It seems that each lesson teaches me something as I am preparing it, and this morning I was challenged to obey God completely, as I give Him the first place in all that I am. Do I really obey Him all the way? Or do I tend to lose interest and quit part of the way through?