I am looking for a word for someone who is willing to make sacrifices or go to extreme lengths in order to get what they want. This is less about how badly they want something and more about how they are constantly prepared to make a tough decision. I'm looking for something more than just "determined" since its specifically focused on how willing they are to go to extremities if they feel its necessary.
Such a person is committed to a cause or course of action:
2 : having made a pledge or commitment to someone (such as a romantic partner) or something (such as a cause) · committed partners · a committed parent/teacher · strongly committed to the fight for equal rights ; also : characterized by such a pledge or commitment . two people in a committed relationship
Also see pledge:
6 a : a binding promise or agreement to do or forbear
b (1) : a promise to join a fraternity, sorority, or secret society (2) : a person who has so promised
As in the case of a binding promise as it relates to a pledge, it means that you will do so something even if it is difficult.
Firm or determined; unwavering.
1. Having or exhibiting uncompromising determination; unyielding
2. Not diminishing in intensity, pace, or effort