Looking at the most recent posts in this thread makes mine look like a total downer

Yes, you can beat sin, absolutely. 'You have to do it' is a big fat lie. I used to think that I'm a completely rotten person until I learned to believe in the simple truth that I
have been made new and God
has given me a new heart that's
good. When you start to believe the truth about what Christ has done and of who you are in Him that should bring change into your life.
Also, it helps to know why you do a certain thing because your past influences your presence. However, it's a lie that you are a product of your past. What took you there is still a good question. Beating a sin can be a long struggle, though. It takes a while to develop a habit and there's usually no quick way out. There
is a way out, of course but you have to be patient with yourself and just hang onto God's strength. Funnily enough, the struggle can become a blessing along the way as you learn humility, to count on others' help and most importantly God.
The point I was trying to make before was that wallowing in guilt doesn't help you any -it only brings the feeling of defeat. When you're forgiven whatever it is you're done, God won't use it against you.
Also, I'd still like to press the importance of having supportive people around you to share your struggle and pray for you. Never ever keep it as a secret!

God isn't looking to embarass you, that's another definite lie.. You know, I would recommend reading a book about spiritual warfare, for example Neil T. Anderson's books are supposed to be good. I haven't been able to finish any, so far, but I did pick up a few useful tips. They're not very light material, just so you know..