I was 24 years old and working at a small office outside of Chicago. Someone came into the room and told us that a plane had hit the World Trade Center. At first, we all assumed it had been a terrible accident.

We gathered around a television in the conference room just before the second plane hit. I remember how completely silent the room became. Nobody knew what to say or what was going to happen next. We spent most of the day calling family members and watching the news together.

What has stayed with me all these years is what happened afterward. People seemed to look out for each other in a way I had never experienced before. Neighbors checked on neighbors, strangers talked to one another, and American flags seemed to appear everywhere overnight.

More than anything, I remember the people who ran toward danger to help others. Even after all these years, their courage and sacrifice are what I think about when September 11 comes around.