What emotion do you struggle the most with?

For me, I don't believe it is a single emotion that I struggle with, as much as it is my own personality and flaws.  Not that I find everything I do absolutely dreadful, but quite on the contrary.  I, unfortunately at times, feel that I do things right and that everyone else does them incorrectly, or not up to my standards.  It's not that I don't make mistakes or overlook things.  I absolutely do.  I am human after all.  I also believe it is ok to make mistakes occasionally.  Everyone does.  But for some people, it seems they just don't learn from their mistakes.  I also have some sort of a mental block.  I feel that if I can do something, anything in particular, that someone else, anyone else, should be able to do the same thing at the same caliber as I.  I am trying to learn to cope with this one in particular.  I certainly am unable to run long distances(or short for that matter) so in that respect I keep trying to remind myself of this example.  But it is so difficult.  Fat people can't run a marathon and some people just can't seem to learn from one certain mistake.  It is a work in progress.  This example doesn't make the mistake any more pallatable, but I'm working on it.