What would you consider your worst trait?

In terms of traits, I mean how one acts, thinks, or speaks. I am not talking about physical traits that are inherited but external ones that are often learned and shaped as we grow older. What would you consider to be your worst trait in that regard?

For me, it has to be my inability to get out of a habit. Once something is a habit for me, I have a hard time stopping it. One example is sitting too much. I am not a lazy person but because I have made it a habit to sit all day (thanks to work and things I enjoy in my spare time) it has affected my health in a negative way.