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. In the long run, a child will bother only if he sees your interest as a form of self-interest, only if doing good translates into feeling good. What transforms moral knowledge into moral bindingness, in other words, is a moral identity, and that identity requires moral objectives worthy of incorporating into one's self-image. Thin gruel such as not running in the halls, chewing gum, or talking too loudly is not likely to be seized as constitutive of a self-image.
Lets get personal.
I'm not proud of doing so. I recognize the risk to my own and others' safety. I think it's wrong. I would stop jaywalking were I penalized with a stiff fine or, worse still, with the stares and disapproval of other pedestrians. Calif. But giving up the habit then did not make me feel more worthwhile, or perhaps only slightly so.