Discipline is the
anchor that a child needs to sail the boat of the
soul. Just as a child needs freedom and imagination, he or she also needs the knowledge that there are rules, that
there is order in the universe, and that they will get in trouble if they put dishwashing liquid in the fish tank.
Discipline doesn't mean pounding your child whenever he or she gets whiny. They are whining because they are tired, or bored, or hungry, or something else that is painful or uncomfortable to them. They are not deliberately whining to piss you off. If you address the reason they are peevish, they will stop. Children hate mixed messages, inconsistent discipline, and ambiguous direction. If you say something, you have to do it, or their trust in you will erode. The more you dissemble, the less they will believe you, and the less they will obey you.
Be consistent. Consistency is the heart of discipline. The reason we hate hypocrites is that they are inconsistent, acting different from their expoused beliefs.