Isaiah 40:30-31 “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 our health conscious world many people have the mistaken notion that hard work and exercise make us stronger. Actually, the opposite is true. Hard work and exercise make us weaker. It is the food we eat and the rest we receive that allows our body to build back stronger after exercise has torn our muscles down. Exercise is a healthy and necessary part of the process, it just isn’t the part that, properly speaking, makes us strong.

From time to time life makes this truth clear to us. We hear of entertainers collapsing on the stage and having to be hospitalized for exhaustion. We instinctively realize we need a vacation after months and months of slugging our way through a grueling schedule. On any given day we can say that we have spent ourselves just to get this far. But tomorrow it all starts all over again. Where will we find the strength to go on?

Isaiah is writing these words for the weary, for those who have nothing left to give. At some point in life, just about everyone finds himself at the end of his resources. Isaiah points out, “Even youths grow tired and weary, and young men stumble and fall.” These young men are the men who were old enough to serve in the army. Picture your well-muscled, physically fit Marine or Navy Seal, ready to face whatever the enemy throws at him. But eventually even such tough and hardened soldiers grow weak, and stumble and fall under the strain of battle.

Whether or not your life has brought you to the very end of your strength at this moment, I’m betting that something in your past has tested the limits of your endurance. Maybe it was something in your family. Maybe it was a health issue. Maybe it just has to do with your overstuffed schedule. You spend too many hours at work. You have too many responsibilities for which you have volunteered at church or at school. You have too many projects that need to be done on the house. You’re stretched too thin to do justice to any of the things that need to be done.

As difficult as these things are to deal with on a purely earthly level, there is a spiritual dimension to this as well. That weariness we know as despair is a great danger to our spiritual health. That’s why, when Luther explained “And lead us not into temptation” in the catechism, he mentioned “despair” by name. “We pray in this petition that God would guard and keep us, so that the devil, the world, and our flesh may not deceive us or lead us into false belief, despair, and other great and shameful sins…” This is one of our toughest spiritual battles. We may so want to repent – literally, “have a change of mind” – of our despair, but our weary sinful flesh won’t let us. God seems more and more distant. Where can we find the strength to go on?

Isaiah promises that the Lord will renew our strength. “But those who hope in the Lord will renew their strength.” This is not a “self-help” approach to finding strength for a weary soul. Isaiah is not a motivational speaker trying to pump us up with a new attitude, leading us to reach down deep inside ourselves to draw on some untapped spring of optimism. That well went dry a long time ago.

Instead, Isaiah is leading us to draw on the promises of God and his word. Those who hope in the Lord do so because God has given them something real to hold onto. He has demonstrated a love that delivers his people from trouble time and time again.

When sin and guilt threatened to crush us, he sent his only Son to push us out from underneath them, and to be crushed by our sin and guilt instead. Now forgiveness fills us with hope.

When we are afraid that we are not going to have enough– enough to pay the bills, enough to put food on the table, enough to survive– he promises, “Seek first the kingdom of God, and his righteousness, and all these things will be given to you as well.” And the fact that we are still here today is proof of his faithfulness. We have enough, and God gives us hope.

When death comes knocking and seems to present the ultimate proof of God’s failure, the indisputable rationale for despair, Jesus promises, “I am the resurrection and the life. He that believes in me will live, even though he dies.” He converts death into the doorway to an even better life, and we have hope.

These promises are like a bungee cord connecting us to God. Though we may feel like we are falling headlong to our doom, and the cord stretches further and further, and it looks as though we are about to splatter ourselves on despair, the promises snap us back up before we reach the bottom. As long as we stay attached to the promises, we have hope.