The question is always the "self". "I" fight for Hashem. "I" do for you. "I" had a bad day. The reference point of my existence - is me. I feel my self-identity very deeply. And the paradox is, that when I hold onto to the self, I do not truly have it.
You see, it could be that we truly did - and do - for others, and even for Hashem. But our reference point is always our own self.
We over-focus on what the 'self' should be doing; what Hashem wants of it; what our wives / husbands / children / Rebbeim, and even GOD(!) want it to be. And when we feel that we are not fulfilling those perceived requirements to others, the VOID IN THE SELF IS HUGE! The 'self' begs to be medicated! FILL THE SELF! Because we focus on the self so much, and deem it empty.
We need to realize that the self just is. That is what is meant by "living for God". Not what "I" should be doing. What does the "I" have to do with it?
R' Aharon Kotler once said - I would jump in Hell itself to understand this Rashba. He didn't care for the self, the self wasn't suppose to learn the Rashba, the Rashba was to be learned!
We need to learn not do for others because we should be doing for others. But to purely do for others - empty of pretense, of desire, of hope, of SELF... And that is the deepest expression of the true self.
This is so essential in any healthy relationship. We should not be in a relationship with anyone "BECAUSE" or "SHOULD" or "HAVE TO" or "HASHEM WANTS IT SO" or "MY SPOUSE WANTS IT SO" but simply because the world is meant to be a certain way. Nothing to do with ME. I am part of the world. I am in harmony with the world.
Here's a metaphor:
The good violinist plays the notes that the conductor wants. But the Master violinist? HE IS TOTALLY UNAWARE OF THE VIOLIN, OF THE SELF, OF THE NOTES THAT SHOULD BE PLAYED OR WHAT HE IS DOING.
To him there is ONLY THE MELODY! ONLY THE ORCHESTRA! ONLY THE MUSIC!
And this is the deepest self. The fullest and truest self. And we only taste it when we totally let go of everything and hear only the beating of our own hearts and existence, and the song of the tzelem Elokim within us that truly has no individuality but is merely part of the melody of Kavod Shamayim which must fill the world. And there is no US. Only the Music!
And if we fall, well, the melody must go on. What does my fall have to do with anything? Guilt? Pain? That's again the "Self"... I
If we fell- well, the melody is Teshuva, and then onward!
NO pretense. NO desire. NO goals. Just Music!