I am not a proponent of the Single Self theory. We wear variations on the various roles, job-titles and social labels we are given. Masks if you will. The masks can take on a life and personality of their own and when we are weak-willed and/or merely superstitiously enthralled they can lead us and change us. Jack Vance touches on this briefly in the first of his Planet of Adventure series The City of the Chasch. 
The tribal nomad humans that the hero Adam Reith meets incorporate masks (or Emblems) and the Emblems' personalities into their society. Reith's first companion, Traz Onmale, wears the Emblem of the tribe's leader (Onmale, the origin of his surname) but Reith convinces him to give it up and escape the tribal life with him. Be observant of what mask you are wearing when and if your actions are of your core self or the mask. Learn to exert yourself above the Will of the mask. Learn to give in to a mask when it best for a situation.
This can be used for self-programming. Uncle Al used to use a large ring, probably some gaudy Masonic thing, and each finger would be assigned personality traits. He would exercise his Will so that when the ring was on say the vegetarian finger, he would act accordingly.
This may seem similar on a lower scale to when we fetishize objects into being our "lucky" T-Shirt or "holy" underwear. However in these cases we think the object comes to us with these special 'magical' properties already endowed, having nothing to do with us ourselves as higher beings. Like that T-Shirt came from the factory cosmically attuned to help Favorite Sports Team win or your G*d only approves of those in certain mass-produced undershirts.