I encountered many students with such misconceptions of their math ability when I taught as a grad student for two years. With many of these, it turned out they had a strong talent for it, they just didn't have a good pre-college math education. I would tell those students that they possessed a good ability at it and encourage them to try pursuing a math-related career.
I don't know if I made a difference in that regard, but it appeared to help bolster their confidence in themselves a little. Educators should do more to reinforce their students and help improve their passion. The state of our K-12 education system is horrid overall here in the US.
