Claire Messud — American Novelist born on December 30, 1966,

Claire Messud is an American novelist and literature and creative writing professor. She is best known as the author of the novel The Emperor's Children... (wikipedia)

The effort to create a work of art that is true and potentially lasting, that is the very best work of art you can create at that point in your life - a book that may only reach or move a few people but will seem to those people somehow transformative. That's the ideal; that's always the motivation.
I believe that, in an ideal world, writers would feel free to write what matters to them without having to consider success, failure, the market, etc.
The more accurately one can illuminate a particular human experience, the better the work of art.
As any of us approaches middle age, we inevitably come up against our limitations: the realization that certain dearly-held fantasies may not be realized; that circumstances have thwarted us; that even with intention and will we may not be able to set our ship back on the course we'd planned.
If I had to summarize, most broadly, my concerns as a writer, I'd say the question 'How then must we live?' is at the heart of it, for me.