I'm with you! It wasn't my first half, but it was my first BIG half ... and the minute we got to the corrals, I was COMPLETELY overwhelmed. I was by myself (my husband was in B, M was in C and I was in D). And it just felt so enormous and overwhelming to me, I'm pretty sure I put my sunglasses on and cried. Well, I mean, I KNOW I cried. I hope I tried to cover it up. It took me forever to mentally get on my game in that race, and then, when I was feeling good and where I wanted to be ... my headphones died. On the river trail. Which was gravel, just like I tripped and fell on back in July. All I had were my thoughts, the sounds of shoes around me on the gravel and the desperate mutterings of the man next to me that kept saying "Nine miles down, only four to go. You can do this. Left right left right. One foot in front of the other. Don't give up." I'm pretty sure I cried then too.
I shot myself in the foot before that race even took off. But you know what? It's ALL part of the learning curve. Mentally, I'm MUCH stronger now than I was a year ago. You just gotta believe in yourself. And, yes, technically you need to put one foot in front of the other.