Use sex to master the discipline of being in control. The more disciplined you are with your urges, the more you are able to enjoy them, because you become a master over them, and not vice versa. The illusion of all urges is that the more you satisfy it, the more you are satisfied. But when it comes to urges, especially the sexual one, the more you feed it, the more it wants. Even in the context of marriage, excess makes the relationship base and self-centered.
Balance is essential.
Anything precious is worth concealing. It is no coincidence that as society becomes more promiscuous and revealing, the quality of relationships and the specialness of sex goes down. One of the best ways to avoid abuse is to create a protective fence. If you're on a diet to lose weight, you stay away from places that serve fattening food. So too, if you want to keep your eyes and mind where they belong, avoid going to places where you will constantly encounter temptation.