The 17th century Puritan Jeremiah Burroughs wrote the following in his book "The Rare Jewel of Christian Contentment",
"A well tempered spirit may enquire after things outside in the world, and suffer some ordinary cares and fears to break into the suburbs of the soul, so as to touch lightly upon the thoughts. Yet it will not on any account allow an intrusion into the private room, which should be wholly reserved for Jesus Christ as his inward temple."
What a great and peace-giving reality this sentiment would give to a troubled soul if one would just learn to relinquish the most inner "room" of their heart, and let Jesus fully reign their unencumbered by your worries, your doubts, your limitations or the world's endless barrage of attacks and temptations. It is often quite difficult to keep our heart separate and unaffected by the day-to-day goings-on in our lives. Whether it be things happening to us outside of our control (other people affecting us by their behaviors) or simply by our own actions and thoughts that cause our hearts to be greatly unsettled and burdened; our hearts often fall victim to a peaceless and discomforting existence.
But in spite of the disturbing realities that go on both around us and within us, we are still called to have a portion of our being set aside which is not ruled by the the world or by our faults and weaknesses, but rather to be ruled by the King of Peace, Jesus Christ. It is interesting to note not only how often Jesus called for his hearers to have peace in their hearts, but just as important is "when" he spoke for that peace to exist within them. For myself, the most important time in which Jesus called for peace to exist within someone was when he first appeared to his disciples in the Upper Room after his resurrection. When Jesus suddenly appeared in their midst, the very first words he spoke to the disciples were "Peace be with you" - John 20:19. What is important to note here is the context of what was going on surrounding Jesus' appearance and uttering peace into their lives.
Firstly, the disciples were without Jesus, their Lord and Savior. He had been crucified three days earlier, and so the disciples were a "scattered flock" without a shepherd. Secondly, it was dangerous for the disciples to be out in public because of the governing view that to be a follower of Christ made you just as guilty of God-dishonoring blasphemy as Jesus was; the world was their constant enemy. Thirdly, the specific place where Jesus appeared to them - in the Upper Room as they were alone with doors and windows shut keeping them completely separated from the world.
Regarding the first point, Jesus is the one who will bring us the peace and contentment we so desperately need. Jesus does not command us to have peace, and then leave us alone to find that peace ourselves from some alternative source. But rather he is himself the very peace he speaks of, and it is in him and being with him that we will find that peace and contentment of heart. We are not to seek that contentment out in the world or by some other means, but solely in Christ alone.
Regarding the second point, Jesus did not appear to the disciples and say, "I'm here now, so I will take away all your troubles and give you an easy life without difficulties or persecution from the world." No, instead he granted them peace "amidst" the outside threats of harassment, and even possible death from those who hated them. In other words, the peace that Jesus offered the disciples was to co-exist with persecution, not to eliminate that persecution. Contentment in Christ while being persecuted was Jesus' gift, not the taking away of that persecution.
Regarding the third point, it is important to know that Jesus granted them peace and contentment as they were alone in secret with him. The Upper Room was not just a secret room that existed 2,000 years ago for only the disciples only, but rather we are also to have an "Inner Room" in our hearts today where Jesus will meet with us in secret and grant us peace there that will govern our souls amidst the outside storms that go on close by outside our hearts.
So as we continue our journeys through this world encountering constant self-styled rulers who wish to conquer our hearts, let not an unsatisfying world reign tyrannically over your soul, robbing you of much-needed peace, but rather give the throne of your heart to Jesus, the King of Peace, and let him have sole sovereign rule over you to bring to you soul-satisfying peace and to find perpetual contentment in him.
"The reason why you have not got contentment in the things of the world is not because you have not got enough of them - that is not the reason - but the reason is, because they are not proportionable to the immortal soul of yours that is capable of God himself."
- Jeremiah Burroughs, The Rare Jewel of Christian Contentment, Chapter 5, pg 91