I have worn out 3 pairs of Shape Ups over the past several years, I love them, they're the most comfortable sneaker on the market for my money, whether or not they actually do anything to tone your muscles.  They make walking easier and avoid sore feet.  My latest pair is suffering the worn sole syndrome so I went to buy a new pair and was dismayed to learn they no longer make them.  I rushed to Amazon, found some still for sale, and this pair was only $39.  However this same ad had several colors and I wanted to buy 2 pairs, a different color was much more expensive - like somewhere around $100 if I remember correctly, so I bought two this color.  They arrived yesterday, I wore one pair today, they're terrific.  I may keep looking for other colors - I can't imagine what I will do when these new ones wear out!