I no longer have to try and be polite. It now comes naturally to me. Sometimes I do not even stop and think about what the person I'm holding the door open for thinks about me. I have practiced these small acts of kindness long enough that they have become truly habitual.
For those struggling with habitual sins, the battle can be so intense that giving up actually seems like it makes the most sense. But, that's because we only see two options. Giving in to things you know are wrong. Or a daily fight with all your strength and will against those same temptations.
But, there is another option. After practicing long enough, the same temptations you thought were going to be your forever nemesis become weaker and weaker. Freedom itself can become habitual. We simply have to unlearn bondage through practice.