Say “I’m not a math person” enough times and you’ve written yourself a permission slip to quit.

Said often enough, a description of how a subject is going becomes a description of who you are, and the second version gives you somewhere to stop. The sentence is comfortable precisely because it closes the question, so no particular bad evening has to mean anything. Most people who say it were having specific trouble with a specific topic.

Swap the identity back for the facts when you catch yourself. You find this topic hard, today, with this method. Then name the actual sticking point and get help with that instead.