On May 23, 2015, Dave Mackey went out for one of his favorite trail runs in Boulder, Colorado. His intent was to run up Bear Peak, traverse a short ridge over to the adjacent South Boulder Peak, then finish the arduous 3-hour morning loop by running up and down Green Mountain before heading back home.

But while doing a familiar scrambling maneuver off the top of Bear Peak, he suffered a horrific fall that shattered his left leg and put his life in jeopardy. Thanks to the skillful work of Rocky Mountain Rescue Group, Mackey survived the day. But his road to recovery was long, as he endured 13 surgeries over the next 16 months—the last of which was a voluntary amputation procedure that removed a portion of his injured leg below the knee. That hasn’t stopped Mackey, a Hoka-sponsored athlete and Range of Motion Project (ROMP) ambassador who works full-time as a physician assistant.

After getting fit for a prosthetic leg and getting comfortable with it, the three-time U.S. champion trail runner has been on the move again on some of his favorite trails. (Just 14 months after having a portion of his left leg amputated, he completed the 50K at Bandera Endurance Run in under 6 hours on Jan. 6, 2018, in Texas!) Watch his inspirational story below!