I've been commuting to NYC for a long time now - I used to live in Manhattan, but moved way the hell out to the country in 1996, and have been commuting in fairly regularly ever since.
Last week, I came home as I usually do, and I decided to empty out the computer backpack and make sure some of the cold-weather additions (hand warmers, extra hat & gloves) were all there.
It's amazing how routine degrades into complacency, and how that leads to a a lack of preparedness.

- The battery in my Ham Radio HT was nearly dead
- I had no AA batteries in my bag at all! Not a ONE!
- The one FLASHLIGHT I had in my bad was a fantastic Coast brand light, the batteries were fine, but as I remembered later, it was that goofy "N" cell light, not a proper AA or AAA light. That's gotta go.
- I had only a .5 liter bottle of water on board
- My FAK was missing a few supplies (see my other post for that)

So, all in all, not a total disaster, but it was a reminder that it's a constant need to make sure what you carry is actually ready to go.