Children are too little to know/understand the world as well as their parents. They just want to play and eat tasty snacks all day long. Though they go to school at a certain age, most of them don't know the purpose of studying. They don't have a clear aim for the future until they become respected by doing some things which/that are considered challenging by others. Then they realize the importance of being part of the world. They begin to plan their life and academic studies that can help them become what they wanted to be when they grew up, such as a doctor, a professor or a scientist. They try their best to discipline themselves. Playing with toys, watching TV or sleeping aren't their priorities. They fight against all their bad habits. Achieving a small goal will usually inspire them to achieve bigger goals. So, the most effective way to discipline a child is to let them know what it means to be a grown up and that they are able to change the world and help others after growing up. They only need to have an aim, then everything will be centered around it until it comes true.