Heavy pants

Keys
To get into my house. Duh.

Wallet
It has my identification and money.

Bus pass
Free rides to wherever I need to go.

Pen
Never know when I'll need to write down that girl's phone number. I'm old fashioned. Paper and pen always beats out...

Cell phone
My lifeline. Literally, as it has all my emergency contacts in it. I also jot down life thoughts in there. And I tweet from it. When you know someone who got in an accident, and the paramedics didn't know who to call, you start using the ICE system.