Incorporating speed workouts into your weekly training regimen is a good way to mix up your routine and a great way to help prepare your body for higher intensity workouts, and especially racing. The key is finding one (or, ideally, several) you can find fun yet challenging and be able to modify them to continue to be both.
High Intensity Interval Training (HIIT) Workouts
Non-Interval Speed Workouts
*Finding a friend or training partner with similar goals and abilities can really help take some stress out of a speed workout!