Our decisions come from self-interest and intending to recognize desired ends. Mercer:
MARK MERCER. IN DEFENCE OF WEAK PSYCHOLOGICAL EGOISM. Erkenntnis 55: 217–237, 2001.
“To understand what another has done is … to have a … description of the action he has performed, one that reveals it to be intentional … to know an agent’s reason for performing … action involves understanding his motivation in doing it. … It is not enough, … to understand what a person who intentionally sips from a saucer of mud has done … An interpreter has also to comprehend what in desiring to sip from a saucer of mud was attractive to him. … One way is to connect that piece of behaviour to one or more of the strange agent’s self-regarding ends. If we can see in sipping from a saucer of mud a way of maintaining self-respect, or even a way to delight in the taste of mud, we can understand the desire the agent had to sip from a saucer of mud. We need not connect his self-regarding end to an intention to realize that end in or through his action; we need only … connect it to an expectation of realizing it.”
And, this lays the basis of normative egoism. Mercer 2:
“weak … egoism is the doctrine that all actions are performed in expectation of realizing self-regarding ends. … egoism is the doctrine that behind any action whatever that an agent performs intentionally, ultimately there lies the agent’s expectation of realizing one or more of her self-regarding ends, an expectation without which the agent would not have performed the action. … if an agent does not expect to forestall his own unhappiness or to promote his self-image, …, in … performing an action … then that agent will not intentionally perform an action of that type. … some other self-regarding end, not as a consequence … but directly as part of engaging in that activity, … To enjoy tennis is to take pleasure in playing tennis, and not, … to attain experiences of pleasure through playing tennis.)”
So, we are moral in intending to further our own self-interest. I don’t deny that there are decisions that are to benefit those external to the self but we are motivated to take those acts in trying to recognize self-benefiting ends.
So what my case means is pretty simple. People should only really do what's within their own subjective self-interest. Meaning that if it's not within my self-interest to clean my room, I shouldn't have to clean my room.