Summary: Nothing will steal the joy of your Christianity like struggling with your purity.
"I made a covenant with my eyes not to look lustfully at a girl"
Before I was a Christian I was an immoral, impure, club-hopping religious guy. I was enslaved to all kinds of sexual sin, relationships, pornography etc. Now I am a happily married man who has the privalage of working for the Lord, helping others in their relationship with God. What happened to me? Did I take a magic pill and my life change? No no nononono. I still have the same sinful nature, but thanks to God I have direction and guidance to keep my away from the snares of sin in my life. There are many influences that can help someone be pure, lets talk about two of them.
"This is the verdict: Light has come into the world, but men loved darkness instead of light because their deeds were evil. Everyone who does evil hates the light , and will not come into the light for fear that his deeds will be exposed. But whoever lives by the truth comes into the light ..."
John 3: 19-21
We must get real brothers. We will wither away otherwise. The world uses lust to sell everything, we know our own weakness. Anybody and everybody can struggle with impurity, is it not everywhere?. I have served in the ministry for twelve years, I have a loving wife and two amazing children, this helps me stay motivated to be pure and righteous, but it also increases my shame when I fall. If I am not wise, I will become the man I used to be before I was a Christian: a man enslaved to lust. Impurity can strip a man of his dignity. I thank God that I have Christian brothers that can talk openly and honestly about our struggles and call each other to be pure. My best friend is also a minister and we call each other all the time, we frequently call to confess our struggles and temptations, with the expectation that we must stay pure for God.
Confess to a friend that will listen, but also expect you to change. Get open! Also, if being open is a real struggle for you, try writing it down first and then let someone read what you need to confess.
2. CUT OFF THE SOURCE
"If your hand or your foot causes you to sin, cut it off and throw it away. It is better for you to enter life maimed or crippled than to have two hands or two feet and be thrown into eternal fire."
I hate my sin. I hate the guilt, and the way it makes me feel. But I must also realize that I love my sin.(otherwise, why would I do it?) Your sinful nature loves to sin. You might not feel like sinning now, but you will. Jesus says to cut off the things that cause us to sin. I don’t watch TV after midnight. I love watching sports highlights, but if it goes past twelve, off goes the TV. Watching TV isn’t sin, but it can lead to sin, so I cut it off. You know the things that will lead you to sin. It could be the internet, going off alone by yourself, magazines etc. It’s not worth it. That’s what the Lord says. Jesus says it’s BETTER to sacrifice your "hand" than to let our sin lead us away from God (hell).
Don’t try to "tough it out". Get humble and make no provisions for your sinful nature. Identify the source of your struggle and take steps to cut it off however possible. Also, tell a friend to hold you accountable to it.