I finished listening to Oona Out of Order by Margarita Montimore (wow - that sounds like a pseudonym, doesn't it! I didn't google to find out if it was.)
Basically, when the clock strikes 12 on NYE (which coincidentally also marks Oona's 19th birthday), Oona wakes up in her 50something year old body. And, each year, she wakes up in another year in her life (this is the "out of order" of the title). Internally, she is aging normally, which is why the book is easy to follow - the narrator is "in order", even though her life is not. I started out really liking it, but later got annoyed by some of the years. I'm not going to think too hard about it, and say I give it a thumbs up. It certainly gave me some surprises. But, for goodness sakes, 50 is NOT OLD!
Now I'm going jetsetting off on a Mediterranean cruise with a dysfunctional family in Reese's latest bookclub pick.