All great comments here. And, confidence is king, so take along whatever you have to in order to feel assured. You'll learn over time what you could have left behind. I still drag a lot of stuff with me, but less and less every time.

Also, don't sweat the jitters and lack of sleep. If it is any help, the night before my first century, I never did get to sleep. Just too keyed up! But, I finished in 8 hours, just fine for my first one!

Don't psych yourself out.