There are worse places to be at 6am than along the shores of the Boulder Rez watching the sunrise. True to Boulder running style, the race announcer called runners to the corral about 5 minutes before the starting gun for the full marathon – four laps around the Rez. Five minutes later, the three-quarters marathon launched – three laps. After another five minutes, the half started – two laps, followed by the 10k – one lap.

I met 50-year-old Keenan Haga, from Louisville, south of Bo...