John Grisham, how does he do it?

[online.education]

He published the following non-fictions to date:

* A Time to Kill (1989), ISBN 0-922-06603-5
* The Firm (1991), ISBN 0-385-41634-2
* The Pelican Brief (1992), ISBN 0-385-42198-2
* The Client (1993), ISBN 0-385-42471-X
* The Chamber (1994), ISBN 0-385-42472-8
* The Rainmaker (1995), ISBN 0-385-42473-6
* The Runaway Jury (1996), ISBN 0-385-47294-3
* The Partner (1997), ISBN 0-385-47295-1
* The Street Lawyer (1998), ISBN 0-385-49099-2
* The Testament (1999), ISBN 0-385-49380-0
* The Brethren (2000), ISBN 0-385-49748-2
* The Summons (2002), ISBN 0-385-50382-2
* The King of Torts (2003), ISBN 0-385-50804-2
* The Last Juror (2004), ISBN 0-385-51043-8
* The Broker (2005), ISBN 0-385-51045-4
* The Appeal (2008), ISBN 0-385-51504-7

Among which, I read ...

* The Firm
* The Client
* The Runaway Jury
* The Partner
* The Street Lawyer
* The Testament
* The Brethren
* The Summons
* The King of Torts
* The Broker

And I'm currently reading The Chamber. Obviously, I enjoy reading his novels. There are writers who write a few 'hit' novels like Dan Brown. That itself is a major accomplishment, but what amazes me about John Grisham is that he's so consistent. He writes one book every year, and it typically has over 150,000 words. He's prolific. And ... almost all fictions made bestsellers. How does he do it ...?