1. Get curious about the story you have been telling yourself, and actively challenge limiting beliefs and assumptions you have about yourself.
2. Set goals that are realistically attainable, but that will push you outside of your comfort zone and scare you, just a little bit.
3. If Calm > Excited > Nervous > Anxious is a continuum, try to stay as close to excited as possible.
I also recommend checking out my post: 3 Tips for Getting Past a Slow run. If you are looking for a book to read to inspire you to run faster, check out my reviews of Running Within and Running With the Mind of Meditation. Both of these books have helped me become a faster runner!