Being a teenage male comes with a lot of challenges. One of the greatest challenges is that guys that age tend to think that they know everything. I constantly rationalized my promiscuity. "I am monogamous," I would say to myself, "at least I only sleep with my girlfriend." Stuff like that is what I would say to myself to rationalize my sin, though, even as a stalwart atheist, I knew in my heart of hearts that what I was doing was wrong. Eventually, I couldn't even use the previous excuse I mentioned any more. I had my first "one night stand" at 16. If premarital sex made me feel bad, that made me feel awful. Of course, excessive consumption of alcohol was involved in that one night stand.
The human sex drive is a powerful thing. Because of humanity's Fall, though, it has become corrupted. I understand completely that chastity is a difficult virtue to follow. When asked by the disciples what they had to do to be saved, Jesus said, "With man, it is impossible. But with God, all things are possible." That, I feel, applies entirely to chastity, too. If you are a virgin because of outside forces (parental control, friends, etc.) then it probably won't last. It is a skin-deep commitment. Real chastity requires a strong desire to honor God and honor yourself. It requires you to see your value as a human being, a unique individual whom God knows and adores. It requires you to love your body in Truth; by saving it for your spouse, not doing with it what you wish.
Jordan