I retired for the 2nd time 5 years ago. I've remained active with exercise including walk/running 3 - 5 mi daily and participated in several 5K marathons. This past September I developed plantar fasciitis in my left foot that frankly took me to my knees. Walk/running was out of the question. I saw ads for the Protalus products but kissed them off as overblown. Went to a podiatrist for professional advice and ended up purchasing custom orthotics at $400 bucks. They worked to some degree but did not provide the relief that I had hoped for, especially at that cost. So, I decided to waste another $80 bucks just to see. Bought M100's. WOW. These things are fantastic. Broke them in according to the instructions. Along with daily stretches and on-line home treatments, I am back to pain-free walking. I mean PAIN-FREE. Put the expensive insoles into a corner in the closet. Will start running again soon. Thank you Protalus. I'll be ordering additional devices soon.