The key to defeating the enemy attacking your thoughts:

Philippians 4:8
“… whatever is true, whatever is honorable, whatever is just, whatever is pure, whatever is lovely, whatever is commendable, if there is any excellence, if there is anything worthy of praise, think about these things.”

Take your thoughts captive. God did not give you an anxious mind. You are created in His image. Meditate on His truth. Listen to what He says about you.