I have just completed the Burgess Shale hike, which can be considered a "grunt" hike that an "averagely fit adult" would find difficult to make. I will preface this comment by stating that I had made a number of smaller hikes, including the Sulphur Skyline hike at Miette Hot Springs, the Lake MacArthur hike and the north to south trail-head hike of the Wilcox Pass including several similarly moderate rated hikes as preparation for the the Burgess Shale hike. Furthermore, I run 8-10 km on average every second day. Although I am in relatively good shape, and am conditioned to tackle the Burgess Shale hike, I found the 10+ hours of hard ascent/descent, with a small pack, somewhat fatiguing. That being said, even the fit 27 year old hikers in our group found the hike tiring. Consequently, I would encourage you to be physically prepared before you consider taking on this 22 kilometer (13.75 mile) round-trip hike, which requires you to climb/descend approximately 760 meters (2508 feet) vertically. Be sure you are prepared and then enjoy the spectacular valley views and fossils that you see.