Ascetic

Ascetic n : in the days of the early church, an ascetic was a person devoted to a solitary and contemplative life.  This was characterized by extreme self-denial, and self-mortification and total devotion; a hermit; a recluse; hence, one who practices extreme rigor and self-denial in religious things.

Ascetic can be an adjective that applies to someone who turns away from his or her material comforts to follow a path of rigid self-discipline and self denial.  It is usually done as part of an act of religious devotion and even spiritual improvement and enlightenment.  Persons associated typically as leading an ascetic existence are usually hermits, monks and religious devotees.  The word itself is derived from Greek.