Sometimes when I start to feel very smart and proud of my life accomplishments, I start feeling paranoid that I am actually inside a simulation like The Matrix whose sole purpose is to keep me from realizing that I am the dullest fool among my actual peers in the real world. I imagine that the mind-blowing "AHA" moments in my life are the most embarrassingly obvious conclusions to my real-world pers who are all far, far more intelligent than me, and that my entire life is nothing but bumbling around and rediscovering their most basic common knowledge.
If you frequently have difficulty in accepting that you might be "good" at things and frequently find ways to explain away your accomplishments, or reasons that someone who compliments you might be mistaken, you should look into this subtle type of depression:
http://en.wikipedia.org/wiki/Dystimia
