A race training plan, especially a marathon training plan, is made up of several different training periods. Each period corresponds to your ultimate goal. Remember, that each workout is in your plan for a reason; it's there to make you a stronger runner up the hills or understand how to push through fatigue.
In order to reach your runnng goals, it's important to remember that each workout is a step towards that goal. You'll accomplish great and lofty goals by doing the work (the small, yet tough, workouts).