Being a sadhu is the fourth stage of the life of a Hindu, after studying, parenthood and pilgrimage.
There are different processes of becoming a sadhu within the different Hindu sects. They are usually initiated by a guru, given a new name and their own mantra. The mantra usually remains secret, known only to the master and the sadhu. Although some practices of the sadhus might seem extreme - such as being silent for years, sitting in a cave for a long time, or standing on one leg for many years - others include practices such as Hatha yoga, devotional worship of a deity, or meditation practices.
Sadhvis start their hermit life after the death of their husband and often live in isolation and ascetism. In some sects, sadhvis are considered a form of a goddess and are worshipped.