MUP beat me to it, but I'll just add my +1. In my case it's a definite FWIW, because I'm nobody's mother and I make no claim to understand your struggles (I sure empathize though)!

But consider that your kids are learning that their best isn't good enough, and that if they don't know ahead of time that they can do something perfectly, they shouldn't even attempt it. You don't even want to know how I still struggle with this - or how dirty my house gets because it's not "worth" starting to clean unless I can commit two or three days to get it spotless from the windows to the carpets and blinds.