Runners follow an out-and-back loop course in Frank G. Bonelli Park at the San Dimas Girls on the Go Half Marathon, which starts and finishes along park roads at the southern end of the Puddingstone Reservoir. From there, the course unfolds nearly all the way around the lake and is virtually pancake-flat throughout, save for a few rolling hills here and there. The turnaround point is tantalizingly close to the starting line, and then you’ll retrace your steps back for the race finish.
(MORE: Girls on the Go Half Marathon San Dimas event details)