Discipline is very important in our nutrition. Eat when you are hungry. Hunger can be in the eyes and in the mind, too, not only in your belly. Learn to distinguish that.
Eating is fun, no doubt, but it is not fun anymore when it becomes a habit.
Make one meal a day a meeting point, a ritual for the whole family together.
Be aware while cooking and eating that you are doing something important. Love your food and don't waste it.
Respect your food. Your stomach is not a garbage box. You are doing something important when you are eating.