The pain in your knee, though you know not its cause, is not without purpose, nor is it a sign that God has turned away from you. For whom the Lord loves He chastens, and scourges every son whom He receives. Do not imagine that a righteous life is free from affliction; even if a man appear untroubled, hidden trials are never far off. The narrow and difficult road leads to life, and the broad way of ease to destruction. If you would enter into rest with the saints, you must walk the same path they walked, the path of hunger and thirst and hardship, the path Paul and Peter trod, who never found ease in this world but endured all things for the hope set before them.
Consider how affliction trains the soul. A body pampered with luxury falls quickly into sickness, while one kept low fights off disease. So too a soul given to comfort is easily overthrown by sin, but affliction schools it in patience, and patience in proven character, and character in hope, hope that does not shame us. You are not being punished as an enemy; you are being trained as a son. Do you not see a father corrects his child, and the child learns what is good by it? How much more does our loving Lord use pain to draw us from vain pleasures and to steady our wandering thoughts. In times of ease, even David grew careless and said, “I shall never be moved.” But in affliction he learned to say, “Let Him do what seems good to Him.”
Do not therefore be troubled because you cannot trace the source of the pain. This uncertainty itself may be a mercy, keeping you from anxious speculation and turning you to the only true Physician of souls and bodies. Cry out to Him, pour out your groaning before Him, for He hears the afflicted. Yet do not demand relief as though you were worthy; approach rather as the Canaanite woman did, seeking mercy for your misery, ready to accept whatever answer He gives. If He delays, it is not cruelty but a call to press nearer. If He grants healing, give thanks and remember the lesson. If He permits the affliction to remain, accept it as a gift no less precious, a weight to press you into the mold of humility.
Look around you at those who suffer for worldly gain, they bear far worse things for a fleeting reward. You, for the hope of eternal life, can surely endure a knee that aches. This light momentary affliction is working in you an eternal weight of glory beyond all comparison. Do not add to your pain by grieving immoderately; such grief benefits nothing and only deepens the wound. Instead, give thanks in this very thing, knowing that tribulation is a great good, a schoolmaster to make you wise unto salvation. Endure it bravely, not drawing down suffering upon yourself, but when it comes, bearing it as a man whose heart is fixed on the city to come. Then you will find, with the apostles, the power to rejoice even in much affliction, for the Spirit gives joy that the world cannot touch.
Flee to Him who permitted this trial, and say with the prophet, “It is good for me that I was afflicted, that I might learn Your statutes.” So shall your knee become a step deeper into the life that is in Christ Jesus, to whom be honor and might forever. Amen.