Accept even before you begin writing that the final draft of your story or manuscript will likely look very different from the first draft.
There are variations on the saying “writing is revising,” but they get down to the same point: writers will likely spend more time revising than they did writing the first draft.
By mentally preparing early on and reaching a level of acceptance of what’s to come, you help to lower your resistance when it’s time for major cuts, additions, reorganizations, etc.
The right mindset—that is, the knowledge that your writing WILL change between drafts—can also lower some of the anxiety and make you more open to feedback from critique partners, beta readers, editors, etc.
Bonus: If you’re a classic perfectionist like me, this mindfulness may also help keep you from getting caught up in “fixing” during the initial drafting.