I'm pretty surprised at some of the responses from Christians regarding the thread topic. I can only suppose that most of the Christians who think that heavy petting and near-intercourse are okay are teenagers or in their early twenties. But you should consider a few things about sexual impurity. I speak from experience. I'm 34 now and have been a christian for 22 years. I never wanted to have sex outside of marriage, but I went to far withone girl when I was 23, and she had a baby who died eight hours after birth.
1)You are a NEW creation. When you became a Christian, your sin nature was crucfied with Christ, and the Holy Spirit moved in and empowered you to walk by faith. Why do you want to settle for walking in the flesh, when God's calling is for you to be pure and walking in the Spirit?
2)You have heard it said "Hey, I'm a human. It's completely natutral. God understands. he's not gonna blame me for something I can't help". In fact, you may have said it yourself. Well, I've got to tell you that kind of thinking is a lie - straight from Satan's demons. They want you to believe that you'll never be free from impurity, so that you won't live up to God's standards. But you CAN be free! God doesn't want us to be wallowing in sin, and he doesn't excuse it. He gave you the Holy Spirit and made you a new creation. The old sin nature is dead! What you are obeying by being impure is one of 2 things (1)Lies whispered in your ears by demons or (2)old habits of the flesh. Your spirit, the new creation in you, wants to do live for God.
So what to do about it? Give it up to God - realize that in your own human power you can't consistently overcome temptation, but by his power alone can you win the victory.
Remember, "I can do ALL things through Christ, who strengthens me". That includes overcoming sexual temptation. Don't let yourself get into situations in which you can possibly "go too far". Don't let your hands stray. Don't kiss heavily, as that always spurs people into wanting more.
Train your eyes at all times. You see a scantily-clad woman walking down the street? Turn your eyes away immediately. Don't risk taking that second glnce. Same with inappropriate clothing in movies. And Department store ads. Don't give sin a chance.
Train your mind. If a crazy sexual thought hits you, remind yourself that you are a new creation and that you are not allowed to dwell on those thoughts, and that you can do all things through Christ who strengthens you. Don't dwell in the thought...replace it with worship for God.
If you start to replace the bad habits with the new good habits (eye turning and worshipping), those new habits will come very easily to you - automatic even.
There is a new series of books for men about overcoming sexual impurity. There is one for adults called "Every Man's Battle", one for teens (I think it is called "Every Teen's Battle" and another one. They're by Stephen Arterburn and Fred Stoeker. They are very good books that contain a good guide to winning the victory once and for all. They don'taddress the "new nature" aspect quite enough for my tastes, but they are very good, nonetheless.