Guilt can be a very healthy stimulus to change our behavior for the better.
Unfortunately many people seem to be nagged by a pervasive sense of guilt which stays with them no matter how moral a life they lead. Psychologists have written reams trying to differentiate between guilt and shame, but the best way to describe the difference is to evoke our own feelings. For a few minutes he fantasizes asking her out his suave charm sweeps her off her feet and before you know it they are in bed. He feels powerful, manly, irresistible. To me this example conveys the essence of shame.