Done twice. First time I was in great shape and didn't hiking boots and I honestly didn't find it that challenging. However the second time I did it just recently I wasn't as in shape and I didn't have my hiking boots on. I wore sneakers and believe me that was a grave mistake. I slipped I slid I fell no fun. I highly advise hiking boots or trail running sneakers at the very leas. As long as you have some grip you'll be better off. It's a really good workout and very strenuous. I plan to do it once a week to monitor my progress for both fitness and weight-loss and of course, for the physical challenge of it.