It is a common misconception that experiencing Shamanic ecstasy or embarking on that first shamanic journey makes you a Shaman. It is more complicated then this.
Not everyone can become a Shaman...it is a terrible experience to survive a calling and thus one should not "wish" to be a Shaman.
However, anyone may still benefit from the experience of practicing Shamanic techniques and ecstasy without being a Shaman.
A Shaman is a master of the Shamanic abilities, journeying, ecstasy, even healing.
A Shaman is also one depended on by some form of a group or community, while I believe one might be a Shaman to their own Brotherhood or family, in most cases this is a village or some nation of people.
To these people, the Shaman is their window between the worlds. So to answer the question, there are three ways most Shamanic Traditions agree one can become a Shaman.
1- By birth into a Shamanic family, one can receive the hereditary right to be a Shaman.
2- One might be called as a Shaman. Often a person will become seriously ill (physically, mentally or psychically) during this calling.They will then realize, or be informed of, their calling. Once the person begins their training and accepts their calling, they will be freed of their illness.This calling is not a request, but rather a divine command. Once may be raised in a Christian family which rejects the path of the Shaman, but to ignore the call would not be acceptable. Most Shamanic cultures believe that rejecting a call is a fatal mistake. Surviving the call is what gives the Shaman the experience needed to begin healing others.
3- One may choose to become a Shaman.This involves an intense, personal quest towards being a Shaman, including the traditional training and studying. According to "orthodox" beliefs, a Shaman who chooses his path is less powerful.
Many cultures believe there is no such thing as one who chooses to be a Shaman and such a person is either fake or simply unrespectable. Survival of the calling is part of the experience and to choose this path is to surpass the calling.
Regardless of the way one initiates the journey, it is a very tough and devoted path to follow. A Shaman must endure intense physical discipline, days in sweat lodges, seeking visions, long journeys between the worlds, and deep study of deities, myths, the secret language, and their heritage.
This is why Shamanism is not a religion but a way of life that becomes the nature of the individual.
Suggested free e-books to read:
Hugh Evelyn White - Hesiod The Homeric Hymns And HomericaWilliam Phelon - Our Story Of Atlantis
Ann Groa Sheffield - Groa List Of Recommended Heathen Reading
Tuesday Lobsang Rampa - Doctor From Lhasa
Leo Ruickbie - Halloween And Samhain