DC's full of military people and the fact that I take the Metro each work day to the stop across the street from the Pentagon allows me to come in contact with more of them than the average American citizen.

Since I've sold my car and depend totally on public transportation (with an occasional cab ride thrown in) to get me to where I need/want to be, I've pretty much put the downsides of public transportation ("crazy" people/"sick" people/the thought that it would be really a coup for some terrorist organization to blow up the DC Metro system/etc.) out of my mind.

To mitigate these risks, however, I will generally sit or stand within the general vicinity of a person in uniform. I figure if bad stuff does happen, maybe I'm next to someone who's been trained to handle it.

It makes the ride a lot smoother for me in some "security blanket" sort of way.