I was in college, but had no classes that day. I woke up that morning around 8, and I was going to see @darkchylde28that morning. On the way over, I couldn't find any music on the radio, just the news on every station about a plane that had hit the WTC. The trip to his house was fairly short, so I didn't get that much info, but what I got was indicative of a small plane, probably an accident. I thought, oh, that's sad, and turned the radio off. I got to his house, came in, and sat down to wait on him to get ready (for whatever we were going to do, which we never did.). Before I was there for a full 2 minutes my mom called me on my cell (one of those Nokia bricks), and said "TURN ON THE NEWS!" We turned it on just in time to see the second plan hit, which I think based on the time was probably a replay. We watched for a while in shock.
I left a little later, I couldn't hang out at his house for long because his mother smoked like a chimney and I got sick if I spent too much time there. So I went to my mom's house (my parents were in the middle of a very bad divorce) and watched the coverage, and cross stitched to calm myself down. I still have the Christmas tree ornament I made that day. It's an angel cat with a toy mouse in it's mouth. I dated it, 9-11-01. I figure it'll be a family heirloom someday.
The next day, I went back to classes. I was a Criminal Justice Major, I wanted to be a cop like my dad. My first class that morning was Police Issues in America. I remember the professor (and the class) was great, but his lecture was obviously not what he'd planned. Instead we talked about PTSD. He gave us a timeline. He said "In five years, you'll see the survivors will be suffering from these symptoms, and in ten years they'll have these symptoms." He walked us through the timeline for what the survivors (police and otherwise) were going to go through for the rest of their lives, which might be ruined by PTSD, survivors guilt, and serious mental health issues.
It was almost as traumatizing as watching the towers fall, my eyes were opened and I recognized all the habits and PTSD symptoms of my dad (remember the divorce was happening) and all his friends in the lecture. I thought "I can't do this. I can't do this to my future husband and children." I spent the rest of the semester lost, unable to find something else to do with my life, but knowing that I couldn't do that.
So that's how 9/11 changed my life.