Problems: What is the moral significance of a resolution to "amend one's life"? Disordered affections cannot easily be reformed, and not ordinarily reformed in one act. Why? On one hand we resort to thinking of vice as any habit: it is difficult to change because it is a settled disposition and has become inscribed (in some sense) on the person possessing it. But in the case of vice, the matter is more complex. The governing "logic" of a human being is multifarious, having many disjointed parts -- parts which are relatively independent, without direct reference to each other, and which function in some cases almost automatically. The unity of the person is not grounded in a unity of will, because the will, as a secondary intellectual power, is informed by intellectual habits. It is true that the will is the governing power of the rational soul, but also true that, just as our intellectual habits are not (except in unusual cases) monolithic or perfectly systematic, the moral habits of a person are not organized according to a perfect unity. For a person resolving to reorder his affections to be effective in this resolution, that person already needs to have governance over those affections. But this is often not the case, notably (in the case of vice) when the logic motivating the undesireable behavior is at odds with the logic motivating the resolution to change. The problem is exacerbated when the former is unrecognized by the latter, giving us "compulsive" behavior. The "hidden" (often because it is too obvious to be noticed) logic governs some set of behaviors or coping mechanisms which tend, in accord with particular judgments and circumstances, to kick in, contrary to broader principles of action.
It might be tempting, then, to assume that a "healthy" individual has an "integrated consciousness" or something like that. But this seems to be unrealistic. The field of interests and occasions encountered by the average person even in a single day is too diverse to be governed by one, monolithic logic of action. Instead, what we have are diverse principles of order which come into play or fall out of use depending on the circumstances and prejudices at work in a given moment. Virtue ethics, especially in Aquinas, respects this perfectly. Notice how little time Aquinas spends on the questions of the universal goodness or evil of individual acts (4 questions), in comparison to the vast set of treatises devoted to the particular principles governing action: the Passions, Habits, Law, Grace, Gifts, Theological and Moral Virtues.