It can be so hard to guard your heart when the world wants to lure your heart away from God. Whatever you open your heart to will determine your actions. Let God's word into your heart, let it fill your mind with what is true, honorable, right, pure, and lovely.
Proverbs 4:23 "Guard your heart above all else, for it determines the course of your life."
Pray and ask God to put a deep conviction on your heart so that it can't be controlled by the world.