A great movie, in my opinion, is one that tells a familiar story in an unfamiliar way.
A true artist could and should create till the day they die. You don't ever fail as an artist until you quit being an artist.
When I set out to write a screenplay, I have in my mind a beginning and an end but that end part continually changes as I start to write the middle. That way by the time the screenplay is finished I have taken myself and my audience from a familiar beginning point through the story to an unfamiliar ending point.
My advice to aspiring actors and writers is that your career's success is totally your responsibility. You need to make it happen. There is no end point to an artist's work, no set time line you have to live up to.