I have a few easy things I like to do if I'm that discouraged and tired. I'll do reading in a "general" book (broad history book with pictures, for example) or go for a walk for a specific purpose (my neighborhood has a zillion rabbits and I often count rabbits going out/into my neighborhood; on foot there are often some I can't see from a car).

I think of some aspect of my problem and see if I can figure out one thing to make it easier for me and just otherwise let my mind roam where it will, often it will see something pleasant or think a thought that will make me feel better.

Letting my mind expand in some way often makes me feel less tired and hemmed in. Sometimes writing in a journal or working on my own quiet projects (sewing, organizing, etc.) can help too.