This final friendship challenge of the year is simple but surprisingly powerful: write one friend a genuine letter. Not a text, not a quick “thinking of you,” but a real note that names why this friendship matters to you. In this episode, Nina recaps all eleven past challenges from 2025 and explains why December’s challenge—putting your appreciation in writing—can shift a friendship in a way few gestures can. She offers ideas for choosing the friend, prompts to get you started, and a reminder that the message doesn’t need to be perfect to make an impact. A quiet, thoughtful way to close the year and strengthen one connection that means something to you. Special thank you, as always, to my assistant producer, Rebekah Jacobs!