Recipe for a Career: is it a main dish or side vegetable?

As a student and practitioner of career planning, I am always in search of the definition of a successful career.  What enables success and how is it defined?

I was reading Amy Poehler’s book, Yes Please, recently and stumbled across her brilliant definition. 

"Career is the stringing together of opportunities and jobs.  Mix in public opinion and past regrets.  Add a dash of future panic and a whole lot of financial uncertainty.  Career is something that fools you into thinking you are in control and then takes pleasure in reminding you that you aren't.  Career is the think that will not fill you up and never make you truly whole.  Depending on your career is like eating cake for breakfast and wondering why you start crying an hour later." 

I think she touches on something that each one of us has to wrestle with in our careers: is it going to be our life’s main dish (something that defines you) or is it a nutritious vegetable (something you do because you need to)?  Or, for the lucky ones, is it dessert?  Something you choose to do because it is sweet and makes the whole meal better?