Example: Let us say your WoW character has the engineering skill and you want to build the flying machine. As with all things in entertainment, the motivator is because you want said thing.
So you will head to an area and do whatever is needed to gather up the raw materials required. This could mean digging up ore, to finding out what character in the game sells a hula doll.
When you are farming for an item, you come across others who are doing something similer or the same. This can lead to conflict as the resource may be limited and you both want the same thing in the same amount of time. In some cases one or the other will move to a different location, other times some odd battle for the goods, will take place. It is just human nature even when your a big cow man.