1) Most training paces should be based on current fitness. If you have not raced recently you can take some of the guesswork out of your training by using a current performance.
2) Using an equivalent performance chart you can evaluate your progress towards the bigger goal. Are you on track or do you need to adjust your goal to a faster or slower or time?
3) High intensity training boosts your running economy and getting a t-shirt and maybe even an award sure is more fun than doing it on your own.
4) Racing with regularity allows you to cash in your hard work more often. If you wait for just one or two races a year and the variables do not cooperate on the right days you may not have much to show for all your sweat equity.
5) Make a shorter race part of a longer run. Want to get great long run training effect without running even longer? Go into a little energy and muscle fatigue debt and add miles of training effect to the same distance long run.
6) Support your local running community by participating in quality races. No matter how good a race may be it will not last without strong participation. Volunteering also counts for this one!
7) Many training partners and lasting friendships started by meeting someone at a race. Running alone or in the same group is fine but occasionally meeting new runners outside of your normal circle can be great, too.
8) Expand your sense of the possibilities. Be encouraged and motivated by what you see other local runners accomplishing. If they can do it why can’t you?