not only is it very possible but a good skill to have. not so much "brainwashing" but conditioning the mind (changing thinking patterns) to better ones self. if one is not happy, it simply takes the changing of thought patters to create a happy reality. you choose what kind of reality you reside in.
yeah i think my friends parents brainwashed my friend, cause she lives in her little bubble world thinking everyone likes her and that she has a great life but doesnt, i always think i live in my ow little world and that everything that i think is not what is really going on, do ever think that?
i seriously doubt you could consciously brainwash yourself into believing something naturally that you don't do and/or believe already we aren't capable of intentionally stressing ourselves to the point required to "brainwash" or change ones normal, logical thought patterns i think paranoia, etc can & does cause us to alter our thoughts but not in a healthy way