Jane Austen on Self-Control - and the Lack Thereof

... it was not a subject on which either of them were fond of dwelling when alone. Elinor avoided it on principle, as tending to fix still more in her thoughts, by the too warm, too positive assurances of Marianne, that belief of Edward's continued affection for herself which she rather wished to do away; and Marianne's courage soon failed her, in trying to converse upon a topic which always left her more dissatisfied with herself than ever, by the comparison it necessarily produced between Elinor's conduct and her own.

She felt all the force of that comparison; but not as her sister had hoped, to urge her to exertion now; she felt it with all the pain of continual self-reproach, regretted most bitterly that she had never exerted herself before; but it brought only the torture of penitence, without the hope of amendment. Her mind was so much weakened that she still fancied present exertion impossible, and therefore it only dispirited her more.

- from Jane Austen's "Sense & Sensibility"
(Italics mine)