“I failed” is a sentence about Tuesday. “I’m a failure” is a story you made up about forever.

Failing is something that happened on a particular day. Being a failure is a description of a person, and the second one arrives without any new evidence behind it. Grammar does something sneaky there: a verb about one afternoon becomes a noun about your whole self. The second version also removes any reason to try again.

Catch the swap when it happens, usually in the hour after a bad result. Put the date back in the sentence. Say what went wrong, say when, and leave your identity out of it entirely.