One of the most interesting mitzvos in the Torah is the one that leads off last week's parashah, the law of the beautiful captive woman, the yihas to'ar. In brief, if a Jewish soldier comes across an enemy female and he find her attractive, he's allowed to bring her home to become his wife. However, the procedure isn't as simple as slinging her over his shoulder and carrying her off, kicking and screaming. Nor is battlefield rape countenanced.
Instead he must bring her home, shave her bald, give her mourning clothes to wear and then listen as she spends the next thirty days wailing and crying over her parents and her people. Only then is he allowed to marry her.
And if during those thirty days he changes his mind? He must set her free. He can't share her with a friend or sell her to a different master. She goes free without limitation. And if he keeps her? As Rashi notes, the Torah hints that she will become an unloved wife who will give birth to an unruly son. Not exactly the greatest endorsement, eh?
I've always like the drash that says that this halacha can be allegorically interpreted as a man battling his yetzer hara. If you go out to war against your yetzer hara and a sin is presented to you in a desirable way, etc.
What I think we can learn from this is that the Torah is telling us that it is actually quite hard to sin. God, in His infinite wisdom, has created an imperfect world for us to live in with all sorts of temptations to overcome. But in His infinite mercy, He has really made it much easier to be good than we realize. Having been created in the image of God who is good, we are by default all good. It doesn't take effort to overcome sin and reach for purity. Rather, it takes effort to sin and damage that purity.
Similarly, just as we know that it takes proper kavannah to perform a mitzvah in the most optimal fashion, the rule of the yifas to'ar suggest the same for a sin. One does not really commit the sin in the most optimal fashion without making an effort for it. Consider all the effort one has to go through to This is all a sign of God's mercy to us and how He ensures we can always return to Him without feeling despondent that our sins have created an immovable divide between us and Him.
Thus even if one has made the effort to sin and persisted in it, one can still free oneself by simply letting go of it. One can always do a chesbon hanefesh and reach the proper conclusions, thereby endeavouring to return to God which is an especially important thing to do at this time of year.