Fear drives a person into himself. It is the essence of self absorption. It is a result of  sin. Our hearts are sinful and so we have this inner problem that comes to the surface in our actions and thoughts. In reality it is not the thoughts that war against fear but it is faith that is a fear destroyer.
If we have an over abundance of fear we are in a darkened experience. We are beginning to battle most in the mind. The fear rages from the inside then the mind has a fierce battle going on. It is a battle for faith. Fear has a power of control. Living by faith is living on the light of the truth of the word. That state of darkness in the mind through fear battles against the light of the word.
There is a fierce battle that if fought with prayer there will be a deepening of faith by this resistance. Its not necessarily the victory over fear that is reality but the resistance to the fear that gains ground. In order for us to understand the protection we have by faith we must have the light resist these inward forces.If we are driven into ourselves by fear then we must live in that battle so that we gain a greater understanding of our protection through applying the word to our minds in that struggle. When we do this we will grow in faith.
Our hearts will be enlarged, our minds will be convinced through its opposition to trust in the unlimited resources of the light so that it is driven beyond trusting in self. This is an enlarging of the heart to receive a greater abundance of Gods love.
We are talking about a sense in the mind not just the thoughts translating to resist fear. There is a sense of the protection from fear that is mystical in the word being breathed into the mind and irrigating the soul. There is an end in this struggle for dominance. There is a window into absolute peace and freedom, which when in this battle translates into hope for existence in a mystical way in the experience of that peace in God. He ends all fears, in Him. Hope produces force to overcome in this struggle.
Through meditation the mind grasp by faith Gods infinite care by the  promise so that there is a mystical infusion of that care for greater resistance to fear.