"I can't do this."
"It's impossible for me to learn this."
No, it's difficult. It's challenging. And if it's the most challenging topic ever, maybe it's just what you need. Especially when that topic is something which is specifically designed to teach people critical thinking skills.
Maybe I'm biased, as the daughter of a philosophy professor and someone whose career once depended on making practical use of critical thinking and logic. Maybe, as a person who adores the very specific articulation which is only possible with correct grammar, I'm just bristling at the idea of correctly-worded converse statement being called poor grammar. It's perfect grammar; it says exactly what it's supposed to say. It does not say what you think it should say - that doesn't mean it's mistaken.
But really, if you tell yourself you can't, then guess what - you're right!
If your brain doesn't "work that way," it's only because you haven't learned how yet.
If you give up, you'll never learn it. And you won't be able to do it.
To the dear friend who inspired this