I got this from Barefoot Ricks site: http://barefootrunner.org/
I think it’s great description of how to adapt to little rocks, acorns, etc. and embracing the pain.
“In the beginning, rocks and pebbles would hurt when I stepped on them while running barefoot. The tendency of the body, when it feels pain, is to recoil from it. To be successful at barefoot running, one must embrace all feelings that the foot encounters, including the pain. When one accepts the pain of a rock or an acorn that causes discomfort then one is less likely to recoil from it. This causes a feeling of relaxation. When one does not accept the pain, then the body tenses up and rushes reaction to the pain area, which is really energy that need not be expended. If one relaxes, the foot accepts the pain and it becomes less and less when a barefoot runner continually steps on the same object.”