I framed it as, "I'm retiring, and I'd like my last day to be March 13. I know I'm surprisingly young, but this has been a long-time goal for me that I've achieved. I have a lot of mixed emotions, since I really love working with you all [which is true!], but it's time to live out the dream I've had for ## years."
Both my manager and director were very supportive, which is wonderful and says a lot about their character. Sounds like my director is thinking about retiring at 50, so he was jealous in the most friendly way. I feel very lucky, and I know that if we hit a big recession later this year and I need a contract spot to tide us over until the market recovers, I can contact them - the bridge isn't burned. Gods I feel lucky.