I don't know either. But possibly look at it as being kind to yourself when you get something done? Like, for me, I hate attempting cleaning when I'm so depressed, but when it's done it is it's own reward, ya know? Or not wanting to shower, but once its done I do always feel better.
I know being productive and extremely depressed don't go together. But what's wrong with rewarding yourself for getting something done, like a favourite movie, treat, or something small when you've accomplished just a small task, and then increase it from there? Idk but being rough on yourself isn't going to work i think