Books where the main character travels back in time before the apocalypse and gets to prepare for the End of Days

Hey, I have been trying to find books with this premise, I love reading books where they get to prepare for the apocalypse as they know it's coming but I have been unable to find many. Does anyone have any favorites with this premise. I also love apocalypse books that feature them saving animals, as I feel like animals would be a vital resource in an apocalypse.