I´ve already started one, exactly on the day of the 22th of November 2014. My bro has told me to try it, ´cause I´d seen to be too pesimistic and frustrated. Since then I´ve been typing (almost) every single day three positive experiences I´ve enjoyed. Yeah, even if it was just "I survived this fucked up day" or "The bus was two hours late and I didn´t freak out". I dunno if it´s helping me to be more positive, but I am not using it exactly for this reason. It is more like short version of a diary I´m too lazy to write.