In direct interactions with people, I'm actually very timid and polite...maybe even wimpy. On the outside, I am often tactful because I fear conflict, so in that way, I guess I am nice.
However, on the inside, I just get angry when I can't stick up for myself. I tend to resist talking to authority figures that I am directly supervised by (such as a boss or a teacher) or anyone I feel personally intimidated by (I'm personally intimidated by people who, in reality, are no one I rationally need to be intimidated by).
I think it's my niceness that has caused me to lose perspective and the sight of my desires, because I hate hearing the "N" word, which in this case, is "No."
But I don't think that my reasons for seeming nice are the same on the outside as they are on the inside. My niceness stems from fear of conflict, but on the inside, I'm enraged that I can't be more assertive.