Why am I so nervous??

So today I ended up walking around about five miles. My training says to stay off my feet and elevate...hmm? Tonight before going to bed, I will do a ten minute ice bath to prevent any inflammation. The nerves are definitely starting to set in. My dad asked me "I know it's a big deal but you're ready, what exactly are you so nervous about?" Well, good question. I know I have trained, but I guess I am worried about psyching myself out, quitting in the middle, stopping and walking, getting sick - or even worse, injured, forgetting something important and not being able to find it on the course, hot weather...or rainy weather, sleeping past the start time - or worse, not sleeping at all. One thing the coaches have told me to never do is try something new the day of the race. Well...two things actually. I have trained with Gatorade b/c it saved my life that one day at Point Inspiration. When I was in sports basement getting my hand held water bottle holder (which is also a new thing!) the guy said gatorade is too much extra sugar - that it will make my energy inconsistent and could lead to crashing. He said I should do Nuun, which is also what mama lisa recommends, but it tastes like nothing. Opting for the all natural, I buy citrus ginger nuun tabs and fail to buy my lovely power gel double latte packets. This will be the last chance I ever see those again. So I am changing my gear, fuel and electrolytes...sounds like I'm the rule breaker.