There's this old cowboy adage (though to be fair it could be much older, perhaps as old as humans have been riding horses for?) that if you fall off of a horse, the best thing to do is immediately get back on.
And it's really not optional. In order to continue moving forward, you must get back on the horse.
With an actual horse, there are really two-fold reasons to get back on. The first, and typically more admitted reason, is that (generally speaking), when a rider comes off a horse, it's because the horse did something to unseat the rider, i.e., bucking, rearing, spooking, taking off, etc.
This doesn't mean the rider didn't do something to cause the horse to have this reaction. I've seen that a million times, especially with inexperienced riders. But for a seasoned rider like myself, it takes quite the surprise to have a horse unseat you. (And it has happened three times for me: the first, when I was pretty inexperienced myself, was also the worst fall, resulting in an ER visit later that night when it became apparent I actually did hurt myself. The second and third were both off of my own horses, and much milder).
So if the horse is reacting to something out of stubbornness, or a refusal to work for the rider, the rider must get back on--immediately-- to show the horse that despite their attempt to rid themselves of their burden, they will work through the issue with the rider on their back, and they will do so safely. Horses are big animals, and safety is always a top priority with a responsible rider. That same rider will make safety the horse's priority, too.
If it's physically possible to get back on the horse once you're dumped, you must. If you give up and put the horse away, the horse learns that by dumping its rider, it can get out of working any time it wants, and bam-- suddenly you have a horse that will do its level best to dump any rider it can.
Now, the second reason to get back on is to conquer fear (both yours and the horse's, if necessary). If YOU get up and walk away and don't come back for a couple hours, or a day, or a week, by the time you do come back, fear will have had time to fester. And you will be afraid for much longer than if you had gotten back on right away and proven to yourself that you can do it. The longer you're away, the greater your fear. Plus, if the horse reacted out of fear to unseat you, the horse needs to re-do it again quickly to conquer their own fear, as well.
So why am I telling you all of this? Congratulations if you've read this far, by the way-- years as a riding lesson instructor and my general passion for educating people about animals have made me rather less than concise when it comes to this sort of thing.
I'm telling you this because I know that every now and then during this game, I can use a little encouragement. So I'm going to (hopefully) try and encourage anyone out there who needs it right now, whether it be to keep writing, or to edit a draft, or to send another query letter. Do it. Think of your brain as the horse. If you don't keep at it, your brain learns, "Oh! Hey! By not thinking about writing, I can DO OTHER THINGS! This is great!"
And if you're afraid of rejection, the same holds true, as with the horse, too-- the longer you're away from it, the bigger your fear of it grows.
So go! Shoo! Get back on that horse!