Today, write about a time in which you over-gave of yourself, and feel some degree of cringe about that now. Maybe you went all-in on too-big of a romantic gesture that was rejected, or maybe you dropped everything to help someone in a way that seemed right to you at the time but turned out to not be right for the recipient at all. Think along those lines, and write into that.
But also, while you’re welcome to keep this within the bounds of a personal essay, I’d challenge you to push into the topic more and see what more universal layers you might add into your writing that serve and connect with your reader.