“Everything becomes a chore, even things you previously enjoyed, and chores become monumental feats of willpower. Food doesn’t taste good any more, and you don’t actually enjoy eating your favorite foods, but you know you need to eat because otherwise you’ll die, and that would make other people sad and be a big problem for them. (The only reason I have never, ever seriously considered suicide is that I knew it would only create more of a burden for my family and friends. Now I’m finally finally able to accept that it’s actually nice to be alive, though, for hte most part.) So you get out of your safe comfortable bed and force yourself to eat something, and the gnawing feeling in your stomach– a pain you think you deserve to feel, and you might even accuse yourself of being a coward because you aren’t punishing yourself more– is gone, but all you feel now is emptiness. And congratulations, because you took steps toward keeping yourself alive, so now you get to feel more emptiness in the future because to you, that’s all that being alive is! Can you blame anyone for having motivation problems in that case?
Depressed people don’t put in “no effort”. Just eating dinner is putting in a HUGE amount of effort, because you are intentionally doing something you don’t enjoy, which will extend your sentence of pain and misery in the jail that is your brain because you’ll be alive longer. Because you quickly learn that there will be NO happiness, and soon you can’t even IMAGINE feeling satisfied after getting something done. You are trudging through an endless desert, and the longer you walk, the more your feet hurt and the more tired you get, and you can’t even imagine that there’s anything good in the direction you’re walking. Sometimes you stop and take a rest, but eventually you get back up and keep going– motivated by absolutely no hope of reward or rescue, but simply pure willpower. To do that, to act when there is no reward and no hope, when the idea of progress seems like an illusion, takes a MASSIVE amount of effort.
I hope maybe I’ve helped you understand this aspect of depression; I know it’s difficult to imagine if you haven’t experienced it, but it is a very real product of the inability to feel happy, or even imagine feeling happy after you’ve gotten something done. So to look at someone in this situation and say “you’re not putting in any effort” is like looking at someone covered in massive weights and complaining that they’re just walking a bit, not running, so they must not be trying very hard. It can be almost literally paralyzing; I would lie in bed for hours screaming inside my head “Just get out of bed! Get up! Legs, move! Brain, why aren’t you making my legs move out of the bed!? MOVE!!!”