Yesterday I ran three of my four miles barefoot. It was probably a quarter- to half-mile too long. I put my shoes on when my soles start to sting. I have a high tolerance for pain--except for when I'm at home sick, then I'm a big baby--so my soles started to sting about the time a blister developed on each foot. (Of course, that destructively macho, "Just a little bit farther" attitude may have been a contributor.)
Aside from that, I could really feel the difference in my stride. The muscles I use to land on my forefoot are getting stronger. After I put my shoes on I managed to keep landing on my forefoot. But what I really enjoyed was running barefoot on the grass. I felt like a gazelle. Fortunately, I was not being chased by a cheetah. But I did feel faster and stronger. It might be that same delusional state of mind I have when I think I'm riding like Lance while I'm cycling, but that's okay. It's like finding a new happy place to be in.