I always tell the kids that "if I didn't love them" I would let them do whatever they wanted. For exapmle, if someone is not following directions sometimes I say, "If I didn't love you, I might let you get away with that," or, "Aren't you glad I love you too much to let you do that?"
Today I overheard a conversation between two kids:

"If teacher didn't love us, well, that would be a lot of fun."