I've been pretty consistently walking barefoot, or wearing "barefoot" shoes, since the snow melted. I knew it was good for muscle development and helps with balance, but I hadn't noticed much change until yesterday.
I noticed that my toes are pushing with a lot more strength than they used to. I think normal shoes have such stiff soles that our toes don't really exert much force compared to the springiness from the shoe. Without that supplemental force my toes have had to pick up the slack.