Those who think they can do it on their own end up obsessed with measuring their own moral muscle but never get around to exercising it in real life. Those who trust God’s action in them find that God’s Spirit is in them—living and breathing God! Obsession with self in these matters is a dead end; attention to God leads us out into the open, into a spacious, free life. Focusing on the self is the opposite of focusing on God. Anyone completely absorbed in self ignores God, ends up thinking more about self than God. That person ignores who God is and what he is doing. And God isn’t pleased at being ignored. (Romans 8:5-8 MSG)
The mind is used in a good many ways, but there isn't always room for thinking on the things of God. Sometimes our minds get so filled with other thought - shutting out thought of God's grace, his actions on our behalf, and his intense carefulness over our lives. We miss the moments to consider what he has done and continues to do in our lives - all because we get so focused on self. Self is indeed a formidable barrier to considering God - to worship. Worship is a form of 'purposeful thought' - to worship, one focuses their thoughts on the object of their worship. We can worship a good many things. I propose the things we think upon the most - focusing the attention of our minds upon most frequently - these are the things we worship the most. If that object of our attention is self, then our worship is really of all the things that build self up, keep self satisfied, and create a sense of well-being in self.
Self is really demanding - it wants to be satisfied the majority of the time. This is where we get the idea of being 'selfish' - wanting self to get what it wants regardless of the needs of those around us. The thought life focused on self is not easily persuaded toward different thought. It finds no need in thinking of others, or of the circumstances outside of one's own life. Why? Self demands the focus remain inward, refusing to allow the concentration to drift outward. When we are this absorbed in self, we ignore what is right there in front of us. We ignore the things that should trigger actions outside of ourselves. Actions that are directed toward the needs of others are not the object of our thoughts - at least not most of the time. Yes, the selfish thought life can be directed external to self on occasion, but it is not the most common use of one's thoughts!
If we find ourselves a little too 'inward' in our focus, it might just be time to ask God to help us explore the space in our thought life he created for the consideration of the needs of others and the enjoyment of those things he has provided in our lives. If we find we cannot easily do this, we only need ask for his help. He delights in being asked to reorder our focus - to help us be less selfish and more open to those around us. There is no true joy in only catering to self - only focusing on selfish demands. There is genuine joy and tremendous peace in realizing grace delivers us from a selfish mind intent on nothing more than the building up of self. Just sayin!