As usual, Oswald Chambers, as CS Lewis, nails the reason for prayer: in our prayer life, God does not give us the answers we mere mortals want, He gives us Himself. And, if we are willing to accept that relationship, we do find the peace that Isaiah speaks of.
In that context, I would ask for prayers for my brother Greg for comfort and healing. He had mitral valve replacement many years ago. After a recent echo cardiogram, he has experienced internal bleeding. He is in the hospital in Portland, Maine, where they are attempting to strike a balance between the blood thinner he needs, and the coagulant drug necessary to help stop the bleeding. I am flying back there this Tuesday.