Yeah... I don't think anyone "Trains" to become a shaman... lol... I doubt it's a choice... If you're genetically predisposed towards being a Shaman, i'm sure higher learning/training would be useful... But I very much doubt you can pick someone off the street and train him to become a Shaman.

From what I remember reading real facts about shamanism, shamans fall ill with a mysterious illness. Only then are they identified and initiated by others.