Ask for a renewal of His strength
Isaiah 40:29-31 (NIV) 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 not be faint.
In this awesome chapter about the incomparable greatness of God, Isaiah, closes with how God can impact the lives of men. Though He is the high and Holy One, He gives His strength to those who are weary and weak. This is a theme that runs throughout Scripture. God does not help the self-reliant. Contrary to the popular expression, He does not help those who help themselves. He helps those who trust in Him. We must realize how helpless and needy man is. Then we can call out to God with our whole heart, without some man empowered backup plan. Our hope must be in God alone. Then He will meet us with the strength we need to endure.
Time and time again, God's people have come to the end of themselves, and then God has done some great thing through them. It was when the body of Jesus was nailed to the cross and laid in a tomb that God brought about the greatest victory and greatest display of His strength in Jesus. It was when Elijah thought he was finished that God began to use him for the majority of his ministry. It was when Hezekiah had nowhere else to turn that God defeated the Assyrian army. We could go on to some of the modern missionaries. Many of them came to the end of themselves and some even to death before the ministry exploded with fruitfulness.
Whatever your situation or season in life, look to God. Look to His strength. Don't rely on your own wisdom or energy but on the life and strength of Christ.
Consider: When you think you can't go on, and the need is there before you, hope in the LORD, and ask for a renewal of His strength. Then get ready to soar.