Writing is detailed work. In academic writing the details can be overwhelming.
First of all there is the whole intellectual/theoretical aspect--and that is rife with details: on any particular point of theory there are probably a number of different points expressing different ideas about different aspects of the theory. Then there is the whole presentational aspect: the written work. There's punctuation; there are style rules and manuals, and so on. And all those rules have to be checked against every sentence that you write.
In short, writing requires attention to detail. The great difficulty in managing all the detail is one of the motivations for the existence of editors. If you have been looking at a written work for too long, then it is hard to see the work clearly. Editors come to a project with a fresh eye. Granting that editors may have valuable skills and insights that may assist an author, much of what the editor does can be done by the writer: it may be easier for an editor to check spelling, but the author can do that. Similarly dealing with rules, etc.
If you're not going to get an editor to help, the many details can begin to become overwhelming. Indeed, even if you do have someone edit you work, they may give you so much detailed feedback that it is hard to process.
The good thing about writing, however, is that it basically stays still. All those details that need to be attended to? They're waiting, and they will wait patiently for their chance. One need not try to figure out how to deal with all the details; it's enough to figure out what detail to work on next and how to deal with that detail. All the other details will be there later.
By keeping it simple, it's easier to deal with the task at hand. By breaking the work down into the natural increments demanded by the details, you can get in a habit of making progress.