How are the Coach Greg training plan paces (for the half marathon) determined? I have used the calculator on mcmillanrunning.com, using my current and goal race times, for comparison with the Garmin Coach paces, and see there is little correlation. In some cases, the GC paces are much slower than McMillan, and much faster than McMillan in other cases. It does not appear that GC is using or consulting the McMillan training pace algorithm.