Copyediting requires a vastly different mindset from writing and even reading. Your goal isn't to enjoy the writing, it is to make sure that the thoughts of the author are fortified in a solid groundwork of sentence structure, grammar, organization, or whatever type of copyediting you are responsible for.
It's a lot of power for an individual or a small team, and with that power comes responsibility, even though the foundations of copyediting are quite simple: to never introduce further error, to retain the authors meaning, and then some. As a copyeditor for an international academic publishing company, I am charged with making a manuscript "print ready" in terms of grammar and house rules (plus the ocassional spelling error or missed capital letter at the start of a sentence) before it heads to a final review by the author.
While I am reasonably intelligent and can figure out verbiage around subjects like "Transonic Buffet Active Control with Local Smart Skin" or "Mycobacterium chimaera identification using MALDI-TOF MS technology," I am aware that a slight change in punctuation to a phrase, or rearranging a sentence, could change an author's meaning. Considering the myriad ways a copyeditor's effect can be seen on a manuscript (despite our best efforts), here is a list of tips for ensuring an ethical editing relationship with a piece of writing.
"Ideally, copyeditors set right whatever is incorrect, unidiomatic, confusing, ambiguous, or inappropriate without attempting to impose their stylistic preferences or prejudices on the author."
Sources:
What Copyeditors Do, Chapter 1, University of California Press