You have the right idea....put it down for a bit and do something where success is guaranteed...and come back to it later. Preferably when not tired! I usually keep several projects going at once for this reason....right now I have a very stressful, tricky one, a bargello cut and waiting to be sewn, two quickies for my grandsons, and a beautiful one waiting for blocks to be put together. I can always find the one I'm in the mood to work on!