With this next guideline, we’ll be halfway through Kurt Vonnegut’s rules of writing short stories that I’m tweaking to apply to your non-fictional memoir.
Rule 4: Every sentence must do one of two things—reveal character or advance the action.
You might think that because Vonnegut intended these rules specifically for writers of short stories, not even novels, that the word “short??? is key to understanding why a story should embrace Rule 4. But I would argue that even if your memoir is as long as Ulysses at roughly 268,000 words, you should keep this rule at close hand. In fact, I’d swap out “sentence??? for “word???—you should be able to justify the inclusion of every single word you write. If you don’t need a “very,??? a “really??? or an “I think,??? what’s it doing in there?
However, I will permit playing a bit fast and loose with determining what information reveals character or advances the action. In your autobiography, you’ll have to provide explanation and background, which at first glance does not seem to meet either of Rule 4’s requirements but, in my opinion, it certainly can if crafted properly; it’s okay if the payoff does not show up until chapters later. If the sentence truly does not contribute in even a minor way toward revealing someone’s character or advancing the action, though, then I agree with Kurt: your tale is better off without it.