I remember an illustration a professor used once (sorry i can't remember which one) but he said that once we do something or learn something we create a pathway in our brains that is there permanently, that is why many people have addictions or patterns. The same goes true in our spiritual walk with God. People fall into the same sins all the time and wonder why they can't get out. This is where Jesus comes in, we need to ask him to stand guard at the entrance of those paths and listen to him when he tells us to turn around and NOT go down that path of destruction any more! We need to hear his voice when he tries to save us from falling over and over again. It needs to be a constant decision. This is why we take up our cross daily! It's not enough to just ask Jesus into our lives but to obey him and let him guide us in the direction that is best for us!