Deuteronomy 31:6

Be strong and courageous, do not be afraid or tremble in dread before them, for it is the Lord your God who goes with you. He will not fail you or abandon you. 

When the first thought of fear or anxiety enters the mind, cast down the imagination (thought). The Word of God is a weapon against fear and all attacks. The Holy Spirit goes with us wherever we go to guide us on what to say. We are to speak to those fearful thoughts and not let them control our minds.