Here is what happens to many who struggle with addictions or serious bad habits/behavior, etc. It may not apply in your situation but I think what I share will be of help to someone reading this.
The reason some are not able to break the cycle and see more victories in their life is because they quit doing what is right just before their breakthrough. It as if they are pounding and pounding against a brick wall (doing the right things) and the wall is almost paper thin (they are almost on the other side-the side of victory). But they get tired of pounding, the sledge hammer is just too heavy for them. Many times the reason it is so heavy is that they are not truly allowing God to give them the strength to carry the sledge hammer or at times, letting Him carry the hammer.
Anyways, right before their breakthrough they give up. Because they gave up (even though the brick wall had become paper thin) too soon, they did not have success but failure all over again. So, the next time they encounter the situation they do not believe they will overcome because they do not have a good 'track record'. But they are determined to win so they pound away again, but once again, give up just before the breakthrough.
Usually those around them can see them at the edge of a breakthrough and will encourage to keep hammering away, but the person gives up even when they get encouragement because in their mind it just isn't going to work no matter what they do.
So I am saying many times the battle is in the mind, wrong mindsets.
In order to get to 'the other side', to get to victory, to become an overcomer is to have some small successes to bring hope. In other words fight smaller battles where you can get some wins behind you.
The biblical basis for this concept is found in:
Romans 5:3-5 (NASB)
And not only this, but we also exult in our tribulations, knowing that tribulation brings about perseverance;  and perseverance, proven character; and proven character, hope;  and hope does not disappoint, because the love of God has been poured out within our hearts through the Holy Spirit who was given to us.
How does hope come? By going through trials/tribulations/challenges, persevering/being patient, and developing character.
Knowing that God loves us, we are willing to go through trials, persevere through them, let them build character in us, and get to 'the other side'. Now because we have developed character we are more willing to go through the next trial confident (hopeful) that God will help us again.
Hope this helps. I will be putting some of my messages on this subject in my online store. Anyone reading this will be able to download them.
Richard D'Andrea Dover-Administrator