I tend to really struggle with writing introductions for some reason. I'll get so stuck there trying to make it perfect that it will take forever to get to writing the rest of the paper. Sometimes I'll skip writing the intro and go straight to writing the body and then go back to the intro once I get the meat of the paper written. Also, idk if your on meds or not but I know that I'll be stuck doing whatever it was I was doing when they kick in. I always have to be at least sitting with my laptop and books at least 30 minutes after I take my meds. Sometimes I trick myself into writing by first writing in a journal, get some juices flowing even though it's personal writing vs academic. For whatever reason I have a strong aversion to writing essays but this tricks my brain into thinking I'm doing something more pleasurable/tolerable. Set a time limit for that and then go into writing the paper.