How to Manage Your Energies for a Short Time Window

In training, you manage your energies for any one given workout so that you are able to successfully do the following workouts. This is the exact same thing on race day. You could be in the first five miles of 100 mile race and consciously knowing what intensity you need to be producing but not worrying about those next 95 because you've already planned out that stuff ahead of time. Short interval sessions tend to be even better for this because you just end up doing more of them for a single session.