Dealing with Guilt and Low Executive Functioning Days

I get what you mean. I struggle with low executive function, and negative self-talk. I'm not sure if what works for me would work for you or not, but when I was a student and faced this problem, I would just start writing. I wouldn't think about how relevant what I was saying is or if it sounded stupid, or anything. I would just start writing, because generally speaking getting started is the hardest part. Later, when I had something of a flow going, I would go back and reread that first section and edit it accordingly to make it fit better with whatever the assignment was. As for the negative self-talk, I've been told frequently by friends and therapists that we believe what we hear the most, and we talked to no one more often than we talk to ourselves. So in short, it's kind of a fake it until you make it thing. You tell yourself that you've got this and you can knock this essay out in no time, and that it's okay to have a little slip up where you don't get something done for a day as long as you come back and work on it tomorrow. Even if you don't believe any of that, say it to yourself over and over again. It does start to get a little bit easier with time. I hope at least some of this helps!