Lying and stealing are not matters of preference to be practiced when convenient, rewarded, or self-serving. To feel a personal obligation, particularly in a culture that stresses personal choice, requires weighty and worthy objectives that merit abiding commitments. One way we encourage children to be moral is by exposing them to great exemplars, Martin Luther King Jr. and Rosa Parks, for example. We do not tell children they were great because they didn't run in the halls, pass notes, or chew gum. What transforms moral knowledge into moral bindingness is a moral identity, and that requires moral objectives worthy of incorporating into one's self-image.
Genuine morality is a hard sell.
Almost by definition it means acting counter to our inclinations, making others' interests equal to our own. It means telling the truth when telling a lie would be more advantageous. It means refusing to go along with wrongdoing when the consequence may be loss of popularity. It means giving up opportunities for self-aggrandizement and pleasure. In the short run, a child will bother because he fears punishment and seeks approval.