@Mr_NutterButter the good news is that, once you have a world, you know what will drive people to either do acts of good or evil.

a common thing is a magical or highly sought after item. like the triforce.

one i really like doing is nations fighting against each other over their own sets of ideals, where each believe themselves to be the good party.

you can even mix the two, where several nations are all trying to fight or espionage their way into getting an artifact (or maybe even a place, like the Holy Land). one could be doing it secretly so they can gain power. one can be doing it because they believe they are the rightful owner. one could be doing it because it's a sacred artifact to them and they think it is best kept in their temple. like i said, the more you build up your world the more ideas you'll get. not just for the main story either, but also plenty of subplots.

this can also really help form your characters. if you know your world inside and out, and you know what the current conflict is, then you can think about how a certain character would act in that environment/situation.