In the (kinda) time-travel comedy My Old Ass, 18-year-old Elliott (Maisy Stella) trips on a ton of mushrooms and ends up face-to-face with her older self, played by Aubrey Plaza. The older Elliott has some words of wisdom for her younger self: mostly vague bits of advice about slowing down and enjoying more time with her family. Younger!Elliott listens, and finds that guidance useful.But older!Elliott gives herself one more specific warning: Dont fall in love with Chad (Percy Hynes White), the cute boy working at Elliotts family farm over the summer.Younger!Elliott disregarding this advice ends up becoming the movies most compelling theme and a thread that it shares with cinematic masterpiece Mamma Mia! Here We Go Again. (Yes, for real.)[Ed. note: This post contains ending spoilers for My Old Ass and Mamma Mia! Here We Go Again.]At first, younger!Elliot is sure the Chad thing isnt going to be a problem, considering that previously, shes only been attracted to women. But after getting to know Chad, shes smitten, which makes her question her own identity. Still, older!Elliott is insistent: Dont fall in love with Chad! Younger!Elliott waits for the other shoe to drop, wondering whether Chad is secretly an asshole or something.Finally, she confronts her older self, who confesses that Chad is going to die young and break their heart.In this moment, writer-director Megan Park digs into her most interesting message. After hearing her older self rant about how deeply Chads death affected her, younger!Elliott replies with a No. She tells her older self that being young and dumb is a good thing, because if she let fear of the world change her life, she wouldnt be living at all. So shell take the heartbreak, because it comes with the opportunity to get to know and love someone deeply and with abandon.Some time-travel stories let older versions of characters try to advise or interfere with their younger selves, to help them dodge some traumatizing future. My Old Ass represents a twist on that idea: The older!Elliott learns something from the self-proclaimed young, dumb kid version of herself. And thats something we can take away, even without the time travel which is where the Mamma Mia of it all comes in.In the big, glittery finale of Mamma Mia! Here We Go Again, older and younger versions of the main characters all dance together in a big celebration. Here We Go Again isnt a time-travel movie at all, but it does cycle between flashbacks and the present day, painting the story of how free-spirited Donna Sheridan (Lily James) ended up with three potential baby-daddies over the course of one memorable summer. We see all the older characters back when they were young and dumb but also living with a certain admirable fearlessness.My Old Ass and Mamma Mia 2 end with the same message: Your younger self is part of you, and always will be. Even though there are things you mightve done differently in life, and certain outcomes youd want to shield yourself from, theres also wisdom to glean from that young and dumb self especially since that young self is the reason you are the way you are today.My Old Ass makes the lesson more concrete and tangible, with Elliott outright saying it to her older self. Mamma Mia! Here We Go Again weaves it in subtly even if part of that subtlety is a dance party that brings the young and old versions of people together. That ending is a celebration of the past and present, without any explanation as to how its happening. But thats OK, because in a way, arent we all dancing with our younger selves?My Old Ass is streaming on Prime Video. Mamma Mia! Here We Go Again is streaming on Peacock.