Desire and Justification

Is it possible to do something for some reason other than simply wanting to do it?

It seems as though, for any action we may take, if we keep asking "why?", the answer necessarily reduces to "I wanted to." This includes actions we take with an ulterior motive — we follow through with the initial action because we have a desire for something else.

Are some wants better than others? Is it better to, for example, want things that allows future generations of humans to inhabit this planet? Unless we have some external rubric, we cannot say — this want is no more justified than its antithesis.

What's more, if we have a rubric, would we want to follow it? And if we didn't want to follow it, could we say there is something wrong with that? If we frame beliefs as actions (knowledge-actions), we must admit that we similarly have no better reason for believing things than wanting to believe them. That is, even if there is a "rubric" for what desires are "best" to have, we would not be able to justify belief in it.