I guess the way I act overall defines my personality. If I had to say one thing, it'd probably be my strong sense of responsibility for everything that happens to me. If a bus drives by and splashes me with muddy water, I won't stand around complaining about the bus because that doesn't resolve anything - well, maybe I will, but I'll also do something about it.
Although that's not really definitive, it's just something I've noticed because a lot of bad things seem to happen to me. It's either that or my self awareness. Both of these things involve me blaming myself for everything, actually.