He gives power to the faint, and to him who has no might he increases strength. (Isaiah 40.29)
Life in exile is hard. The tempter is busy. There is doubt about the true character of our God. Isaiah responds to all of this. He provides answers to our questions. But, as important as those answer are, they are not the solution. If knowing the right answers is all that is needed, then being able to hang in there would only depend on our being knowledgeable enough. According to this way of thinking, life would be fine if we were able to understand and agree with Isaiah's answers. So, when life gets a little challenging all you'd need to do is pull out answer #3 - or whichever one applied. But what is that but saving ourselves. We'd be rescued by our intellectual abilities and gritty resolve to view life in terms of what we know. Where's the Gospel in that?
Answers are important, but they cannot save. So, Isaiah says more about this God. 'He gives power ... he increases strength. He gives good gifts. And it's because he gives us those gifts that we are able to continue on. Dealing with the struggles of exile is not a matter of thinking better and then trying harder. That will not work. The difficulties are too great. The tempter is too strong. Dealing with the difficulties of exile is a matter of grace. Our Father must give us what we need so that we can endure to the end. He gives the power that we need and the strength to hold on.