Hmm...
Physical, I guess I'll say my height. I'm 5'8", which isn't bad, but when enough women who are shorter than me bring it up enough to call me short, I've developed enough of a complex to be self-conscious about not being part of the 6'+ club.
As far as personality, I'll say my fear of being mean. I'm nice to a fault, which hurts me in situations where aggressiveness is called for. An example would be the stress I've experienced with closing on the house we've had built. The company we went through offered us options in writing, that they later reneged on, saying they don't offer those as of the first of the year, not offering anything in compensation besides a "my bad." That, and the financial department postponed our closing twice because they requested a whole bunch of information/financial history at the last minute that we had to track down. They also failed to arrange a VA appraisal in a timely fashion, and blamed the VA appraiser. Several times, I've fantasized about threatening to back out and ranting about how I don't like their raising prices/cutting costs, yada yada yada, but reasoning always prevails, thinking that there are too many elements involved, not a single point to direct the anger, etc.
I'll also say that I'm methodical to a fault. I don't enjoy being rushed in any circumstances, which hurts me when I'm put in predicaments requiring haste. Me rushing looks like a nervous twit who has no idea what he's doing.