"Do not sorrow, for the joy of the Lord is your strength" (Nehemiah 8:10).
THE GREATEST STRENGTH WE CAN KNOW IS THE STRENGTH OF JOY IN GOD'S GOODNESS. Indeed, the very powers of hell quail before any person whose strength is the true joy of the Lord. And when we neglect to grow strong in this way, every other strength is but weakness. Without joy, our strength is easily broken.
Consider the source of Jesus' own strength. Only hours before He allowed Himself to be crucified, Jesus said to His disciples, "Therefore you now have sorrow, but I will see you again and your heart will rejoice, and your joy no one will take from you" (John 16:22). He prayed to God, "Now I come to You, and these things I speak in the world, that they may have My joy fulfilled in themselves" (John 17:13). John's account says that when the mob arrived to take Him, "Jesus therefore, knowing all things that would come upon Him, went forward and said to them, 'Whom are you seeking?' They answered Him, 'Jesus of Nazareth' . . . Now when He said to them, 'I am He,' they drew back and fell to the ground" (John 18:4-6). All the massed forces of evil in that hour of darkness had nothing with which to breach the fortress of joy within this great heart. Consequently, we are told to look "unto Jesus, the author and finisher of our faith, who for the joy that was set before Him endured the cross, despising the shame, and has sat down at the right hand of the throne of God" (Hebrews 12:2). For nothing less than the joy set before Him, our Lord endured.
In the song that followed Israel's crossing of the Red Sea, Moses sang, "The Lord is my strength and song, and He has become my salvation; He is my God, and I will praise Him; my father's God, and I will exalt Him" (Exodus 15:2). The Lord is both our strength and our song. Is it not clear that He is our strength when He is our song? When we've grown honestly eager to bring glory to God and when showing gratitude to Him has become our greatest joy, then we will have grown "strong" in the highest and finest sense of that wonderful word.
"Love feels no burden, thinks nothing of trouble, attempts what is above its strength, pleads no excuse of impossibility . . . It is therefore able to undertake all things, and warrants them to take effect, where he who does not love, would faint and lie down" (Thomas à Kempis).