Fear
God created mankind in His image and likeness. This means we inherited the traits of God, one of those being power. One thing we didn't inherit from God is fear. I don't know who originally created the abbreviation F.E.A.R. (False Evidence Appearing Real), but at times we can let our doubts or doubts imposed on us by others convince us that the evidence is real.
To conquer the fear we must acknowledge the source of the fear. Is it a physical fear, or something that could actually cause you harm? Fear of standing outside in a lightning storm holding a metal pole would be a wise and healthy fear. Alternatively, it could be a mental fear of your own thoughts making you doubt yourself. If your fears are your own doubts I challenge you to faith your way through it. How? Trust God! Think back to a time when you managed to overcome your doubt or fear.
Trust in the Lord with all your heart and lean not on your own understanding; in all your ways submit to him, and he will make your paths straight. Proverbs 3:5-6 (NIV)