I was recently asked in an interview what was the worst thing about writing.
The answer I gave was revision and the correcting of written work. After reading through pieces 7, 8 or maybe more times, the words and sentences begin to blur and it can become difficult to concentrate. However, on reflection, it is the revision and constant reading through that can make writing become great.
By taking the care to read it through, all the time the work can be improved. Whether changing words, sentences or making deletions, the time you put in can make a difference to the quality - and readabilty - of your work.
I have spoken to aspiring writers who shy away from revision and prefer to move on to the next piece or idea. But it is revision and getting their work as good as they can that will best help them into print.
Paradoxically, what could be the worst thing about writing (in my view), could be the most important.