In the good (bad) old days, many parent disciplined their children with a belt or rod. But true discipline is not simply physical punishment for a perceived wrong; it is training a child how to behave using love and kindness rather than harsh physical pain to accomplish your goals.
No one would smack or belt a little puppy that chewed a slipper or left its calling card on the floor, so why do this to a child? Children should be taught first by example, then by showing them how to do a thing and encouraging them to do it – even doing it with them can work well. Rewards can be given for good behaviour, but little children are so eager to copy and to please their parents that a simple hug is often reward enough.