One thing to remember is that everything is a choice and a trade off.
Perhaps some of the biggest motivations for me are that I notice the change in the way I look at friends - girls, especially any I might want to care for. Those thoughts change the way I view them, would (not might) affect the way I would treat them. I see myself as being here with them to bless them. To encourage them - it is my greatest hope that my life would be used by God to bless others, to encourage them and that I might be a part of God's cleansing, transforming and blessing them - part of God's active creation of their lives! My greatest fear is that I would do the opposite. Instead of being used by God for their betterment and in His plan for them, that I would end up working against God, dragging them down in the areas where they are weak. Polluting their lives instead of encouraging them. I hate that I pollute myself, the difficulty of the stuggles at times, I would never ever wish that upon anyone, certainly not my friends and the ones that I love - yet to keep filling my mind with those things at the least isolates me so that I cannot be used properly to bless them, and worse, it would lead me to become that liability something that is a drain and pollutant in their lives.
Furthermore, and perhaps the most extreme version of this - marriage. I have recently grown quite close to a girl and came to love much about her. But in the process I started to realise that there was much in me that ended up hurting her. Much that put her in difficult situations or did as I said above and lead her to do things which worked against God's will. I wasn't able to lead her as she was hoping and desired or as God desires - I only lead her to dark places. I lead her down not up. And even though we weren't in a full relationship, it was enough to show me that I needed to be very different, had much to learn, if I ever wanted to be a man who could ever really love a woman and lead and honour her as God requires me to. The choice made to dip into porn or lust or wrong thoughts is a like a sweet-tasting poison. It tastes good, and you can't get enough, but every drop you drink pollutes you and means that in the future you will not be able to be the person that you desire to be.
You must choose whether you want the pleasure of the present or the fulfilment of the future - both are wholly available to you, and God is wholly desirous and able to give you the latter. Oh, and the happy little secret is - the present pain of withdrawal doesn't actually last long, and the payoff even tastes sweet in the present. So many new things take on new life, everything seems fresh and real. It's like having been playing games on an aged computer and then switich to a new one. You slowly got used to the quality so didn't think you were missing anything, bu then when you finally make the switch, the reality hits, and everything is so much clearer, faster and better.
God bless,
G.