"Writing that's not working for a living"

In this quote, Robert Asprin is most likely suggesting that composing, for him, is not simply a task or a means of making a living-- it is something more. The phrase "not working for a living" indicates that composing, for Asprin, is not something that he does simply to pay the bills or earn an income. Instead, it is something that he is deeply enthusiastic about or that he feels satisfies him in other ways. This sentiment prevails amongst lots of authors, who often describe their craft as more of a calling than a task. By framing it in this method, Asprin may be recommending that the best writing is done out of love and not just requirement.