Asaph wrote this at his lowest — the preceding verses are a crisis of faith, watching the wicked prosper while his own life falls apart. His body failing. His heart failing. And instead of performing strength, he says the truest thing a broken person can say: I have nothing left.

There's a specific kind of exhaustion that lives beyond tired. It's the kind where you cry in the car before walking into work, then spend eight hours being the most composed person in the room. The kind where someone asks "how are you?" and you physically cannot assemble the energy to lie, so you just smile and nod. The kind where sleep doesn't help because the tiredness isn't in your muscles — it's in your motivation. In your identity. In the part of you that used to care about things you can't remember caring about anymore.

And the answer this verse gives isn't "try harder." It isn't "find a better routine." It's a transfer. God is the strength of my heart. Not: God helps me be strong. God IS the strength. The source. The battery. The thing that keeps beating when your own power is gone. You are not failing. You are depleted. And depletion isn't a moral problem. It's a supply problem. And the supply doesn't come from within. It never did.