We are fragile, but He is not

I just read "What do if you wake up feeling fragile", a short article by John Piper. Don't you feel this way sometimes? I didn't wake up this way today but felt like that some minutes ago. This is for me, but maybe it's for you too.

There are mornings when I wake up feeling fragile. Vulnerable. It’s often vague. No single threat. No one weakness. Just an amorphous sense that something is going to go wrong and I will be responsible. ...
Instead of letting me sink into a paralysis of fear, or run to a mirage of greener grass, he has awakened a cry for help and then answered with a concrete promise.
Here’s an example. This is recent. I woke up feeling emotionally fragile. Weak. Vulnerable. I prayed: “Lord help me. I’m not even sure how to pray.”
An hour later I was reading in Zechariah, seeking the help I had cried out for. It came. The prophet heard great news from an angel about Jerusalem:
Jerusalem shall be inhabited as villages without walls, because of the multitude of people and livestock in it. And I will be to her a wall of fire all around, declares the Lord, and I will be the glory in her midst. (Zechariah 2:4–5)
There will be such prosperity and growth for the people of God that Jerusalem will not be able to be walled in any more. “The multitude of people and livestock” will be so many that Jerusalem will be like many villages spreading out across the land without walls.
But walls are necessary! They are the security against lawless hordes and enemy armies. Villages are fragile, weak, vulnerable. Prosperity is nice, but what about protection?
To which God says in Zechariah 2:5, “I will be to her a wall of fire all around, declares the Lord.” Yes. That’s it. That is the promise. The “I will” of God. That is what I need. And if it is true for the vulnerable villages of Jerusalem, it is true for me a child of God. God will be a “wall of fire all around me.” Yes. He will. He has been. And he will be.
And it gets better. Inside that fiery wall of protection he says, “And I will be the glory in her midst.” God is never content to give us the protection of his fire; he will give us pleasure of his presence.
This was sweet to me. This carried me for days. ...
This has been my deliverance every time since I was first marking my King James Bible at age 15. God has rescued me with cries for help and concrete promises. This time he said: “I will be to her a wall of fire all around, and I will be the glory in her midst.”
Cry out to him. Then ransack the Bible for his appointed promise. We are fragile. But he is not.