Best - a friend of mine messaged this to me when I expressed my concerns and stress about study and life in general in terms of not being good enough and not being smart enough. She's helped me a lot lately.
"Ok, so you're not Sheldon Cooper or Bill Gates. Me either. And even if algebra isn't your thing, it doesn't mean ur not smart. Creative writing is a strength, but not your only ability. And I believe you're well capable of learning a plethora of of other skills and information and proving whoever you want wrong, including yourself."

Worst - this was also told to me by a friend...or should I say ex friend. I had a hard time deciding between this and all the different bad things this person has said in the past
"That's right doing something would require effort and determination both of which you lack"