We function and feel at our best when our skin is making direct contact with the earth's surface, as any excess electrons we gather from our environment can easily escape and let our bodies achieve perfect electronic balance.
The reason walking barefoot in the grass, sand or even concrete feels so good isn't just because your feet are directly making contact with mother nature's elements, you are also making direct electrical contact with the earth's healing power.
Throughout history, humans lived outdoor lifestyles hunting and farming, often barefoot, so they were grounded constantly.