I told a friend I was burning out before I told my manager.

The conversation with my friend was where I learned what I actually felt. She didn't fix it; she didn't try to. She let me say a sentence that turned out to be more honest than I'd meant, and waited while I sat with it. The conversation with my manager came two weeks later, and it got the work to change. But I needed the first conversation to know what to ask for in the second.