For the Spiritual Warrior, that is the one whose quest is engaging in battle with one’s ego self, whose goal is self-change, The Bhagavad Gita expresses it well in Chapter 5, Verse 6. In this case, the Self is one’s higher self, the Divine Within.

Lift up the self by the Self
And don’t let the self droop down,
For the Self is the self’s only friend
And the self is the Self’s only foe.