There is a fundamental and elementary piece from the holy Ohr Hachayim in (Acharei Mos, 18:2) that gives a clear perspective on the powerful nature of these desires, and helps us understand how Hashem expects us to remain holy in spite of it being against human nature. He makes it clear that once a person falls into these sins, it is almost impossible to get out of them without special divine assistance. (This fits in very well with the 12-Step approach which calls sobriety a "miracle" and stipulates that only G-d can keep us sober, one day at a time.)
Click here to download a PDF translation of this important piece from the Ohr Hachaim. To see the original text in Hebrew, click here (the relevant parts are marked in yellow, and the VERY relevant parts in red).
The Medrash on this past week's Parsha says that Pinchas drove his spear straight through the genitals of Zimri and Kuzbi the Midyanite, as they were sinning together. Then, G-d gave Pinchas divine strength and he was able to lift both of their their dead bodies up out of the tent, while still on the spear, for all to see that they had been killed for their sins.
The Holy Ohr Hachaim Hakodesh writes that through doing this, Pinchas made the sin of illicit sexual relations look disgusting in the eyes of the Yidden and thereby caused a tremendous Kiddush Hashem.
On a similar note, the Ohr Hachayim writes as well in another place in the Parsha, that G-d commanded the Jews "Tzror es Hamidyanim Ve'hikesem Osam" - meaning, "Make the Midyanim hated in your eyes and destroy everything of theirs". So the Ohr Hachayim asks, why do we need to hate them and destroy everything, why not be able to benefit from the spoils of the enemy? And he answers that when it comes to immoral sexual conduct (that the Midyanites caused the Yidden to sin in), the only way for the Jews to receives G-d's forgiveness and atone properly would be if they turn their hearts to hate these sins, and destroy all that is related to it. For as long as the lust of the sins remain alive in a Jew's heart, he cannot properly atone for sins of a sexual nature. Instead, he must try to first arouse a disgust and hatred of these sins in his heart - and then he can achieve a true Teshuvah.
The Ohr Hachayim on Parshas Shmos (3:8) writes that before Moshiach's time the Jewish nation will be subjected to the 50th level of impurity. But he also writes, that by using the koach of the Torah, the Jewish people will garner the strength to enter into the very "mouth" of the 50th level of impurity and pull out that which the Satan had already swallowed ("le'hotzi boi'lo mi'piv").
And that is what the GuardYourEyes community is doing today! The Ohr Hachayim Hakadosh could not have used a more divinely inspired analogy! We are entering into the mouth of the Yetzer Hara himself and harnessing the very power of the anonymity and accessibility of the Satan's favorite tool - the internet, to pull out these sparks of Kedusha, these holy souls, that have fallen to the 50th level of impurity!
The Ohr Hachayim says regarding chava and the snake that the reason why she fell was because she allowed the snake to engage her in conversation. Once she got into the conversation, she started entertaining the idea of saying "yes" even though she had originally entered the conversation with the intent of saying "no". She said no, he said "yes", she said "no", he said "why not?"... So she started explaining why not, but by the time the conversation had finished she had fallen through.
This is the derech of the Satan. When we entertain fantasies in our mind, he claims we are just "thinking about it for the sake of saying NO to it". But it's a lie. Because once he gets us fantasizing, we are already in his hands and it gets only harder to break away!
"V'ata Yisroel mu Hashem Elokecha sho'el may'imuch.... ki im l'yirah, etc.... - And now, Yisrael, what does Hashem your G-d ask of you, but to fear him, etc..." and the Torah continues with a whole list of wonderful madreigos.
The Torah is emphasizing that we CAN reach all these wonderful madreigos, if we focus on one thing... V'ata - NOW; not what happened a second ago, nor a day ago, nor a year ago, and also not what WILL happen. Just the present. That is all Hashem asks of us, the ATA - the NOW.