- find a missing Person or Artifact
- find a treasure
- break an evil spell or curse
- destroy an artifact (the ring of power)
- defeat the arch-villain
- investigate a local conspiracy
- guard a Merchant or another traveler or traveling group
- investigate a crime (Murder, theft,...)
- find or explore a legendary place
- rescue or defend a settlement or fortress
In common RPGs, the Adventurers' motivations are often wealth or power; in a Tolkienian background Game-Masters mostly prefer to demand more noble causes. Admittedly even the Legendarium has shady characters: Dwarves out for riches, Elves driven by vengeance and pride, Hobbits driven by curiosity or boredom, Humans motivated by power, influence, politics or pure fate. Some Adventurers became adventurers against their own will (Bilbo Baggins), others start off noble but end up outlaws and tragic heroes (Túrin Turambar). The repenting sinner or a character fighting against his own inner evil, dark heritage, bad fate or a curse could be also be appealing for players.
The schemes of the Dark Lord are not necessarily always the background for every campaign or adventure, rather the general motif serves as the thematic setting in which all kinds of other stories are imaginable: political intrigue, common crime, family feuds, social struggles, romance & drama.