Hi all,
I have experienced this problem for most of my adult life. Thankfully, the Lord is helping to deliver me from this affliction, and He has taught me things which I hope will be of some help here.
I was addicted to pornography and masturbation, and hard as I tried, I could not overcome it. Slowly but surely the temptations would build and I would be overcome. This made me feel hopeless, and I was unsure if I could ever be free of this problem. However, I believe the Lord led me to one day read St Francis de Sales Introduction to the Devout Life, and I performed the spiritual exercises in the beginning part of the book. These exercises made me understand that I was not putting God first, I was constantly putting my own desires in front of my desire for ever-deepening union with God. I asked God to help me re-orientate my life, to be directed solely at Him and helping other souls. Once I did this, once I put God first in all things, I began to get better.
This might sound strange, but this cross Christ has given me I almost consider a blessing now. It made me realise that I am utterly hopeless without Him, I need His saving Grace everyday to get through. If I start to put myself ahead of Him, the venial sins begin to build up until I fall. Try not to tolerate any sin, even the smallest. Pray often, and never skip prayer for selfish reasons, like your favourite TV show. Prayer is the conduit for God’s Grace and it will make you strong in the fight with sin. Give yourself completely to Christ, it is what we are here for above all else.
Sorry for the long post. I have learnt these things the hard way, and I pray that God can bring some good out of my lowly re-counting of the great and merciful things He has done for this poor servant.