Being your own editor is nearly impossible. You write a draft, and then you probably go over it many, many times. Somewhere along the way, your writing acquires what Annie Dillard in The Writing Life calls “the ring of the inevitable.” Your piece of writing sounds good to you because it sounds inevitable, like “poetry known by heart.” It acquires a rhythm that you are unable to alter. One word follows another so naturally, you can’t even dream of interrupting that sequence. It was meant to be. But be careful! Your writing may sound that way not because it is as polished as it can be, but because by virtue of repetition, your writing has settled into a form that sounds unalterable. However, this is not its best form; this is a sign that you need another pair of eyes. An editor will not feel this inevitability. An editor will tell you it doesn't have to be that way, and open your eyes to other possibilities.
So, you get another opinion. Your editor tells you to cut this, this, and this. Your editor tells you to delete that paragraph that took you days to write. It was the hardest part of your piece. It took so much out of you—so much time, so much effort, so much emotion—and now this person is telling you it needs to go. It’s hard, but you have to do it. Leaving something in because it took a lot of time and effort is not a good enough reason to leave something in. In fact, it's a bad reason. Your final product should make the reader think that writing is incredibly easy for you. It is something that you do gracefully, with minimal effort and time. It is a gift you have, no big deal. It may be tempting to let the reader know how hard you worked, but, as Dillard explains, leaving in those hard-to-come-by bits is like giving someone a gift and leaving on the price tag. How tacky. In writing, as in gift-giving, it's not a great idea to let on how much something cost you. So, get yourself an editor who will open your eyes to other possibilities and discreetly snip off that price tag for you.