If we're honest, we have a treasure trove of self-deprecation. You know your foibles better than anyone else. Rodney Dangerfield's "I don't get no respect" attitude is fodder for writing. Mine your own insecurities once in a while; laugh at yourself and encourage your reader to laugh at those qualities in them. It's part of the human condition.
Anne Lamont is a good example. She describes a reading where she had jet lag, the self-esteem of a prawn, and to top it off, she stopped breathing. She said she sounded like the English patient.
Understatement and hyperbole work in writing. Exploit them both.