Right after you’ve written a paragraph or drawn a picture, the struggle to get it right is still fresh in your mind. You can still remember the effort of putting every word and line on the page and you see the moves you are least sure of most clearly. They stand out. When drawing, you are looking at the picture from the same point of view that you were looking at the object and, since you probably didn’t get it perfectly right, its perspective seems distorted, wrong. When writing, you still have the same criticial reader in mind, trying to address exactly their difficulty, and it is painfully clear that you’ve only partially succeeded. Before you evaluate it, put the work away for a few hours, even a few days. Then look at it with fresh eyes.
Or maybe it’s your hands that need to relax. You need to get the feeling of making something out of your body so you can decide what you’ve made. Often, I find the hand looks fine the next day, perhaps just from a slightly different perspective. The paragraph is clear and strong, but makes a slightly different point in a slightly different way. Sure, ideally, I’d want to express my intention exactly, but the important thing is that my lines, my words, aren’t nearly as messy as I thought when I put the task away. You have to remember to enjoy what you have accomplished.