While the other staff were watching the towers fall on the news during work 5 years ago, a physician asked me if I had any "words of wisdom" regarding the attacks.

The only thing I could think of at the time was:
When Rome fell you know what happened? Farmers still planted crops, babies were still being born, carpenters still built houses, and I have patients to take care of.

Maintaining business as usual and living well is often the best revenge.