At the time I was working at the software company in Boston. It was just an absolutely perfect day, weather wise. Other than that it was just another ordinary workday. I remember when the first report of a plane hitting the twin towers came in and I almost thought it was a joke. But quickly reality started to sink in what was really going on. Our phones stopped ringing pretty much immediately and the whole office became eerily quiet.
They shut the office down mid-morning (like everywhere else in town) and it was weird to commute home at that time. We were all in a daze and honestly it's a miracle there weren't a bunch of crashes on the highway. The entire day was a complete fog, the whole country (heck, the world) was in shock and didn't know what was gonna happen next.
I'm not sure exactly how long after it happened (I think it was more than a year after though) I remember driving down to NYC one weekend and went past the ground zero site to see it for myself and it was still a complete mess. I was overcome with profound sadness and essentially just turned around and drove right back to Boston. Shit like that attack on the WTC should never happen...to anyone. But in a weird way I am glad I went to witness it in person. It's hard to explain why, but it did have a greater impact than anything one would see on TV or in the movies, or even by visiting the memorial. My respect for New Yorkers and their resilience was dramatically affected right then and there.
For me, it put in perspective all the other petty shit that people worry about, that's for sure.