Now don't worry, I'm not going to go out of my way to depress you. I'm just going to tell you what I remember about 11 Sep 2001. I have a unique point of view because I was active duty Air Force.
When the first plane hit everyone thought it was a terrible accident, but when the second plane hit everyone knew something was very wrong. It had a surreal quality about it. We had a breakroom with a television and we saw the planes hit, but it still took some time to actually sink in. I think some part of you knows it's real while some part reacts as if it's just a TV show. I still can't watch footage on TV, it upsets me to much.
You'd have been impressed to see the response that I saw. Everyone knew what they needed to do, everyone did their jobs quickly and professionally. Every job, no matter how seemingly minor, was/is important because it enables someone else to do their job. Those were long days afterward. Twelve hour shifts minimum, plus, in most cases, a 40-60 minute commute both ways.
I was exhausted, but I knew I had it easy. Once I got to work, my job was not strenuous, but a lot of people worked long long hours doing back breaking work, a lot of which took place on the flightline which gets very very hot.
Anyways, I'll just end by saying, the next time you see someone in uniform, especially someone older, thank them because they really do work hard to help keep you safe.