>something good isn't good because you desired for it to happen
This is a false statement. Nowhere in the definition of "good" does it say it must happen by chance and never of free will.
I understand you're really posing the question, "Do we ever do anything because it's good, or do we only ever act in self-interest?"
But this ignores the fact that we can desire to do something because it is good. Humans are vain creatures, and they have fought and died for what they believed was right and wrong, for no personal gain.