Atlas, total slacker
There's a nice writing exercise to help exorcise your inner critic. I saw it in The Artist's Way but you may find it in a lot of different variants. It's a visualization exercise. Every writer hears the voice of criticism when they write. And after they write... And before they write... It can be crippling. You can rarely shut it out or shut it up but you can defang it. You start by imagining what that inner critic looks like. Who's making all that noise? Draw it, model it, make a representation of it in some way and then post that in a way that you can be reminded of how stupid and ridiculous and pathetic that inner critic is.
Simple enough. But I don't think it's enough. Just one inner critic? Unlikely.
I would add, to my mental cacophony, at a minimum, the inner martyr. This character is the voice claiming I haven't done enough or that I'm being selfish. It's like a mission specific cousin of the critic, able to cut right to the chase about why I am such a fucking selfish asshole for sitting here putting words in order when I could be doing something that someone else needs. Like programming some shit for them. Or maybe making them a website. Or grading something or putting comments on a paper that a student will never retrieve. Or one of a thousand things that my family needs from me.
If this were psychotherapy, then, yes, of course the inner martyr would be a close relative, like, say, my mother. But I suppose the more colorful visualization is a monk, hunched over and bearing the weight of the world, like the Farnese Atlas but upright (take that, Atlas you fucking lazy non-multi-tasking slacker), tapping on a keyboard answering all the emails that come to him, starting at the screen rigged in front of him as he stumbles ahead, bleary-eyed and exhausted, arising at 5 am and falling asleep mere hours prior.
After he passes, then behind him struts the inner hero, who's just a handsomer, thinner, fitter version of myself. He doesn't actually need to say anything. He just sits there and glows.
And finally, loudly, comes squawking the inner critic. Older British chap blathering on about some pedantic nonsense and how no amount of education and no amount of praise (“”surely they're lying to you about that” he intones) will paper over your clearly pedestrian heritage and utterly unremarkable intellect. I suppose he's an Oxford don or someone of that caricature, clueless and bloated with condescension.
(With no apologies to all the obnoxious academics I have known, from whom my inner critic draws its form, I do apologize for singling out British-ness. It is less that I have met people of this caricature than that it is the collective image that one gets from reading reams of archaic academic prose.)
So they shout, those varieties of the inner critic.
A single inner critic is not good enough. At a minimum, there's a martyr and a hero in there as well.
Every day is an act of exorcism. But they're crafty. And shifty. And able to change costume at will.