Walking uphill as fast as possible at 12,000 feet, my mind racing, no, shuffling, through thoughts of frustration—get it together, Mo, start running. Exhausted and certainly not moving very fast, I swallowed my pride with each gasp of thin mountain air. This isn’t track—this is sky racing. Against my better judgment and instructions from my coach Scott Johnston, I looked down at my watch, which revealed a heart rate number that didn’t lie: 180. Move any faster and I’d quickly turn into roadkill on Kendall Mountain, especially 4 miles into a 12-mile race where my track speed couldn’t save me…