In the end, both virtues and vices are habits that can eventually become “natural” to us. Philosophers describe the perfect achievement of virtue as yielding internal harmony and integrity. Compare, for example, the following two married persons: The first, let’s call Jane. Although she resists them, Jane regularly struggles with sexual feelings for men other than her husband. The second, call him Joe, enjoys an ardent affection for his wife throughout the ups and downs of thirty years of marriage. Are they both faithful? In a technical sense, at least, yes. Jane successfully exercises self-control over her wayward desires. But only Joe embodies fidelity as a virtue. His faithfulness is deeply rooted in who he is. While we can give her moral credit for her efforts, Jane’s faithfulness stays on the surface; it is the uncomfortable voice of conscience countering her adulterous inclinations and keeping her actions in check. By contrast, Joe’s desires are in harmony with his considered judgment. Who wouldn’t rather have a spouse with Hoe’s fidelity than Jane’s self control? The ancient Greek philosopher Aristotle called this the difference between acting according to virtue–that is, according to an external standard which tells us what we ought to do whether we feel like it or not–and acting from virtue–that is, from the internalized disposition which naturally yields its corresponding action. The person who acts from virtue performs actions that fit seamlessly with his or her inward character. Thus, the telltale signs of virtue is doing the right thing with a sense of peace and pleasure. That feels like “second nature” to you? These are the marks of your character.
–Rebecca DeYoung, Glittering Vices: A New Look at the Seven Deadly Sins and their Remedies, pg 16