St. John Paul II details four ways that Jesus' kingdom can take root in your heart.
Jesus is King, but for us to belong to his kingdom, we must first let him into our hearts. This is not easy, as we often deny him entrance to our hearts, letting the kingdom of the world reign there instead.
When visiting New Zealand in 1986, St. John Paul II gave a homily on the solemnity of Christ the King in which he detailed the ways we can let the Kingdom of God take root in our hearts.