Repeats o'plenty! Bring your favorite running shoes. Start at around 50 percent of your full speed and keep an eye on the feel of your lower back, hips and hammies as you fatigue.
Pick a standard for the day. Either fast as you can (once warmed up fully) for 5-7 rounds based on form, or as many as you can at a 5K pace (8 or less rounds).
8 rounds of:
Run 400 meters
Rest 90 seconds
Your score is your total time not including an 8th rest period.
Follow with a good series of nice looooong stretches.