Enough

I was impressed that Ben Franklin decided he was ready to retire once he had "enough". Not the "had enough" that leads one to foolishly walk off a job, but the "had enough" that implies his belly was not empty, he was not thirsty, there were clothes on his back, and a roof over his head. This is the "enough" that seems to be the real challenge.
The line between "need" and "want" should be a simple enough thing. "Need" is requires for survival. Physical need assail us with signals for water, food, shelter, clothing, and medical care. Emotional needs cry out to be loved and to be part of a community. Spiritual needs tend to not crop up while our physical or emotional needs are unmet. If one's belly is empty, there is unlikely to be a strong desire for contemplation of philosophy or theology.