The mental part is, as I've said, out loud. My dear friend in heaven, Lino Ventura, who was the French Humphrey Bogart, once said to me that there are three elements which make for a great film. The first is a great story. The second is a great story. And the third is a great story.
Same thing goes for a book.
They've got to be story driven. And what I try to do is have all those things going on at the same time, sort of like a three ring circus. The other element I strive for is to make fiction read like non-fiction, so that everyone absolutely believes everything that happens. There's nothing worse than a writer who tells you his character turned left and into the bar when everyone knows that bar used to be to the right and is now a GAP Kids. Whatever nourishes the mind.