There is this really amazing article in Rolling Stone about Breaking Bad. In it they have this really insightful analysis of Walter from Breaking Bad, where they sum up his need to continue making meth, in the current season, even after he has made enough money to assure his family's comfort after his death.
Walter, before his cancer diagnosis considered himself a failure, a mediocre teacher, his history a series of lost opportunities when his friends had gone on to make millions. But he is the best maker of meth in the criminal world and that has given him purpose and there has been a point in the show where it became not about his family, but about the work itself, and how he is the best at it, for the first time in his life and that's why he'll never stop.
What I like about it is that it's so specific. Mine has always been too vague for my characters, ie, she looking to gain more power to make up for having her freedom removed from her. It's fine, but the more specific that character core need gets, the better we can keep them true to their core needs, even as plot, or even the world changes.
Here's another one. Vienna from Bachelor Pad wants to be on television so she never has to go back to her minimum wage job again.