The brain is very creative and if you allow it to wander you can find yourself overthinking. Overthinking is different from planning. Planning is visualizing a future event in an organized manner. Overthinking involves fear which leads to our thoughts flooding and getting underwater. We assume the worst. Ask the Lord to take control of your thoughts (2 Cor. 10:5) and find the peace that God will remove the mountains in your life (Mat. 21:21).