Whether it physically hurts or not, it 'works' for a reason. Parenting is hard work. I have a kid around her age that has brought a couple of teachers to the brink of their patience because they don't know how to listen to their kids. By listen I mean empathize. Let them know firmly that you know they must be feeling abc because of xyz, but this is the rules. Breaking them has consequences. There's a lot of great books out there. My favorites are, '123 magic' and 'the power of validation'