One July a couple of years ago, I ran the Four Pass Loop near Aspen, Colorado. As the name suggests, the loop rises and drops four times, crossing four passes in an achingly beautiful swing through the mountains. I ran through haunting Aspen groves, climbed switchbacks adjacent to a waterfall, and trudged along high elevation drainage marshes. 

As much as I enjoyed the vistas that stretched for miles at the top of each pass, this run holds a special place in my heart because it was the mo...