I worry that I forgot something when I left the house for the trip. I'm usually right though. I left our house unlocked on our first trip. I forgot one of my pieces of luggage at home and had to have it mailed to us on our second trip. And for our third trip I forgot all of our poncho's and our toiletries at home.
My wife and her mother are taking bets as to what I'll forget next time. LOL