The basic definitions that I have found portray lust as wanting something or someone you don't and might not be meant to have  or, from a more Augustinian perspective, the perversion of love. While the former is valid, it is not fully complete; the latter is closer to the mark, but only if a very complex, manifold view of love, its attributes, and attitudes is applied.
For simplicity's sake, I shall write from a perspective that, to me, is equally close to the mark, if not closer: lust is the perversion of desire.
Desire is not evil, not in its original intention. Desire seeks something to satisfy it, to appease it. Ideally, this should direct us to God or the God-given fulfillment of that desire. Classically, lust is defined as misplaced or perverted sexual desire, the desire for objects in general and for others' possessions and situations, being greed and envy, respectively.
How, then, does lust play its hand? It presents itself as a temptation, a counter-offer to God's provision for a particular need. In this context, the need could be one for some sort of intimacy, whether it be emotional, physical, relational, etc.. Lust presents itself and its subsequent actions as a source of satisfaction, but being mere perversion of God's provision, it cannot properly fulfill said need.
Lust offers a temporary, hollow, cheap alternative to the proper meeting of our desires. as a result, we can find ourselves delving ever deeper into its offerings as we seek for better fulfillment. In doing so, we condition our hearts and minds to turn to lust's offerings first, becoming addicted as does an alcoholic or a narcotic. Why? Because it provides a thrill, a temporary meeting of a desire for little cost, we continue to seek it out, becoming ever entrenched in its workings.
We're dealing not just with sin, but addiction and, unfortunately, the substance for this addiction is all around us. Advertisements, billboard, magazine, television, or otherwise, provide plentiful source material for the satiation of lust in some degree. Fashion, too, can play a part. So can the media through film, books, and even the radio. Sex sells and, unfortunately, it sells well.
So, if lust's source material is all around us, how does it take place? How does it offer its wares for the individual's "satisfaction"? Visually/mentally and physically.
- Ogling - the visual stripping down of a woman for some degree of sexual power or satisfaction. It is the perversion of appreciation and admiration, both of which, in their pure, intended roles seek to praise God for the beauty of His creation.
- Pornography - the seeking of sexual satisfaction from media. This can be in the form of single images, film, or written text. This also does not have to be depictions of sex and/or nudity. It varies depending on the individual; for one, just the image of a woman in a scoop-necked top could be porn as it incites lust and the temptation to then seek satisfaction therefrom. It is the perversion of the desire for sex with one's own spouse in addition to the perversion of the appreciation and admiration which is to be reserved for said spouse.
- Replay/Fantasizing - the mental recall or projection of a particular image or individual that incited lust. This can be intentional or unintentional, but it is more than simply the image popping into one's head, but rather, the dwelling or expounding upon said thought. This is a perversion of the regard with which one thinks about another, particularly the way one should think about one's spouse only.
- Masturbation - the seeking of the gratification of physical sexual desire by oneself. Straight up, it is a perversion of the desire given to us which should be for our spouse only in addition to the perversion of the form intended for said gratification. Single or unmarried individuals, sorry, but the only proper gratification for this desire is to wait patiently for your spouse.
- Adultery - the seeking of physical sexual gratification with one not one's spouse. Again, the perversion is fairly clear, it is the twisting of what was meant to remain in the confines of a marriage with one's spouse.
As we can see, lust has many faces, some of which may even seem innocuous, but what happens is that one addicted to lust finds oneself completely lacking satisfaction from that which should fulfill it. Relationships, particularly those with one's spouse and with God become cheapened , . It is an issue of the heart, then, of the very core of our being.
How, then, can we overcome lust? Not by our own strength. Convicted of what I had read thus far, I sought to stay pure from lust during my shift at work. The number of times I was tempted to simply ogle an ad, coworker, or customer was surprising, not to mention the number of times a thought from my previous foolishnesses tried to bring itself to the fore. I quickly became convinced, in a more-than-head-knowledge kind of way of the necessity for God's intervention. Sure, I could have kept it up myself, but the strain from just 5 hours was immense. I'm under no illusions that I would have burnt out within a couple of days at best.
We need to become broken. That's Christianese for "We need to realize our helplessness in the face of our sin, discard any last vestige of pride, and humbly come to God in genuine desire for freedom." It is, after all, a hear issue. We need to come, asking for God to restore our hearts to their proper orientation - towards Him. We need to desire God above the false satisfactions of lust. Only then will the war begin to turn. Unfortunately, we cannot change our hearts. We have the unfortunate predilection for sin, the disobedience and turning away from God. It is ONLY through God that we can even be able to come to Him, to obey Him, to truly desire and give glory to Him.
Why, then, do we persist in the illusion that lust and its faces are simply our personal issues, never to be shared with anyone? Why do we enslave ourselves to empty fulfillments and addictions. Let us instead cry out to God. Let us reach out to one another and hold each other accountable for our addictions and trials.
I am human. I lust. I want out.