Follow Parker's build up to the 2021 Boston Marathon. In this episode, Parker does a 24 mile workout on a course that was planned to simulate the elevation profile of the Boston course, but at the mile high altitude of Boulder, Colorado. This workout was a struggle, but in Episode 3, he'll revisit the course and seek his Revenge. The next episode will be a 25k fartlek, a full dress rehearsal for race day.