www.bible.com/111/isa.40.29.niv
Do you not know? Have you not heard? The Lord is the everlasting God, the Creator of the ends of the earth. He will not grow tired or weary, and his understanding no one can fathom. He gives strength to the weary and increases the power of the weak. Even youths grow tired and weary, and young men stumble and fall; but those who hope in the Lord will renew their strength. They will soar on wings like eagles; they will run and not grow weary, they will walk and be faint.-Isaiah 40:28-31
Isaiah is giving us the key to our strength here in these few verses. He begins be saying that God is the creator of everything and that he does not grow tired or weary. He then goes on to say that God will give strength to those who grown weary and will increase the power to those who are weak. The apostle Paul wrote about this to the Corinthian church, “Therefore in order to keep me from becoming conceited, I was given a thorn in my flesh, a messenger of Satan, to torment me. Three times I pleaded with the Lord to take it away from me. But he said to me, ‘My grace is sufficient for you, for my power is made perfect in weakness.’ Therefore I will boast all the more gladly about my weaknesses, so the Christ’s power may rest on me. That is why, for Christ’s sake, I delight in weaknesses, in insults, in hardships, in persecutions, in difficulties. For when I am weak, then I am strong.”(2 Corinthians 12:7-10 NIV). Paul and Isaiah are saying the same thing: you find your strength and power through placing your hope in God. The author of Hebrews put it this way, “Therefore, since we are surrounded bu such a great cloud of witnesses, let us throw off everything that hinders and the sin that easily entangles. And let us run with perseverance the race marked out for us, fixing our eyes on Jesus, the pioneer and perfecter of faith. For the joy set before him endured the cross, scorning its shame, and sat down at the right hand of the throne of God. Consider him who endured such opposition from sinners, to that you will not grow weary and lose heart.”(Hebrews 12:1-3 NIV). God is your source of hope, strength, and power.