Limiting beliefs, such as 'I'm not smart enough' or 'I'm not good at math, ' can keep people from attempting more complex challenges.

CNN: Have an incompetent boss? You're not alone

"I'm not good at math, and there's a lot of calculations involved, " she confided.

WSJ: Ringling Brothers' Air Apparent

I'm not good at math but if you look at it we have to win games right now.

WSJ: Flyers top Sabres 3-2 to end 3-game losing streak