While this idea might seem simple at first, I’d challenge that letting Christ reign as King of your heart is much more difficult than accepting Him into your life. When you make Christ King of your heart you allow Him to have complete dominion over not only your life in general, but every thought and every action that you take. He desires to be the omnipotent, omniscient ruler whom we share everything and ask advice on everything that we encounter throughout our lives. This sounds intense, but that is because it is intense. Christ loves each one of us with such an immense love that He desires this kingship over our hearts. We can take faith in the knowledge that if and when we do make Christ the King of our hearts that He will give us the grace to continue to grow and to love Him more deeply, thereby allowing us to continue to let him rule our hearts.
On this feast of Christ the King, make Christ the King of your heart.