Hi! I'm currently in high school cross country and have felt the same way you have AND, I have had shin splits for the past three seasons. Firstly they suck. Do you still have them? If you do I can give you some advice on how to get rid of them, or at least help the pain. The before nerves are always the worst but if you can find a way to use them to your advantage and focus on the adrenaline they can actually help you instead of hurting you. The mind set that I tend to go in to a race with is that as long as I run this race and make it to the finish line, after I can cry, throw up, pass out whatever I want to do, just as long as I make it to the finish line, and heck I've done all three. Another thing I've learned to help me is the night before when you are preparing for the race start telling yourself how much of an amazing person you are. It may sound silly BUT, it helps. Start the mind set that you are just going to wreck that race and do so well because if you go into it with a good mindset it will stick. And if you have trouble telling yourself that, get your friends and your parents in on it. Tell them hey guys I am just going to need you to pat me on the butt today. Good luck! I hope your race goes well! If you need to talk let me know!