Relax. Keep everything in perspective. If you're going to do all the work in training, why not run hard for the five minutes that you get to race?
Do 3-4 strides, 100 yards long, after every daily run when you don't have a workout. Don't run all out the whole time - run them building from 50 percent effort, then consciously hit 60, 70, 80, and then 90 percent of your top speed. Hit 100 percent for twenty yards at least twice a day.
When you race, don't race to set PRs. Race to beat people you don't like. Hang onto their pace while running as relaxed as you can until 400 yards to go, no matter how slow you think they are. Hang on until 300 to go. Hang on until 200 to go. With 100 to go, do a stride. Go from 90 percent, to 95, to 100.
Become the annoying kid who sprints at the end. If you get used to winning, or just beating people, you'll run with confidence. That's what you need. That's how milers run.