Let me ask you, what do CHRISTians do with fantasies? You don't stop being a human being when you become a CHRISTian. GOD made us as sexual beings and that is a part of who we are. Fantasies are a part of our lives. But what do CHRISTians do with them?
I think if the fantasies in your heart are directed toward your spouse and they're directed out of a heart of love then I'd say the sky is the limit. But if you're having fantasies of someone other than your spouse you need to turn that energy back into your marriage and make it better.
What if you're single? I think the Bible says that we're to use our sexual drive in creative and dynamic ways to serve other people.
Nobody but you and GOD will know what thoughts go through your head. You have the responsibility before GOD to be your own thought policemen. You know what movies you can see. Other people may be able to see all kinds of movies and not seem to be affected by it. But you know in yourself which ones affect you.
You know what CD's bring up feelings in you. You know which books you can't read. You know which TV shows you can watch and which ones send you running for the shower. You know and you have to be responsible before GOD to guard your own thoughts.
Just a thought from the front porch…