Hands-down, this is the most comfortable pair of footwear of any type I've ever owned. They're far better than any other flip-flops, better than Crocs, and better than any sneakers I've worn. I have pretty severe plantar fascitis, which forces me either to be picky about my shoes or endure a great deal of pain. I haven't been able to wear flip-flops or sandals for two years because of it. But after I'd worn these for only two days, my foot pain began to lessen. Now, after ten days of wearing exclusively my Tone-Ups, I'm virtually pain free. In fact, I've just ordered a second pair. I can't say much about the toning, as I haven't worn these for any strenuous exercise. However, the backs of my thighs feel a little bit achy when I walk upstairs, and I have awakened the past three nights to a slightly crampy feeling in my calves, so it's clear they're working my muscles a little differently than I'm used to. I'll take that as a nice little bonus, especially since I'm not doing anything different physically. All in all, wonderful!