If you are a Christian then you do Spiritual warfare against the powers of darkness who send spirits of fear and doubt and unbelief against us by dropping them into our thoughts. If we think on those thoughts by rolling them over in our minds then we are succeptible to them and they rule us and the devil takes us over.
So when I am attacked I take out my weapons and they are the name of Jesus and the blood of Jesus and the Word of God, which is always said Out Loud.
I have memorized scriptures over the years so I do not have to look them up but if you need scriptures on Faith they are all listed on this site:
http://www.blessingmeadowsministries.com/faith_confessions.htm
Lets say the devil has dropped fear into my mind. I immediately recognize that it is from him. I am not fooled at all. I say this out loud because the devil cannot hear it if you just think it.
In the name of Jesus I bind, rebuke and curse that spirit of fear and command it to go now. I have the mind of Christ and hold the thoughts and feelings of His heart. Greater is He Jesus that is in me then he that is in the world. Man does not live by bread alone but by every word that proceeds out of the mouth of God.
I belong to Jesus devil and you have no right to touch me! Now go!
Praise you Lord Jesus that I have authority over the devil.
Jesus even told us Not to take the thoughts that are wrong.
We are to cast them down and if you do not then you will have fear and it will take you over.
Fear is a spirit and you need to be confessing the word of God to stop and block it and cast it out in the name of Jesus.
I always plead the blood of Jesus around my mine and thoughts.
But in order to use the name and the blood of Jesus you need to be saved or the demons will not obey you.
If you want to have God fighting your battles then make Jesus your Lord and Savior and let Him have your life and He will make you well and lead you to your place in Christ.
Here is the prayer say this out loud and mean it.
"God, I recognize that I have not lived my life for You up until now. I have been living for myself and that is wrong. I need You in my life; I want You in my life. I acknowledge the completed work of Your Son Jesus Christ in giving His life for me on the cross at Calvary, and I long to receive the forgiveness you have made freely available to me through this sacrifice. Come into my life now, Lord. Take up residence in my heart and be my king, my Lord, and my Savior. From this day forward, I will no longer be controlled by sin, or the desire to please myself, but I will follow You all the days of my life. Those days are in Your hands. I ask this in Jesus' precious and holy name. Amen."