Writing a book is very personal. It's a very personal relationship. A book will start with something as simple as two men talking about work. That gets the fire going. Sustaining that fire is the hard work. It takes attention and empathy to hone the characters.
I don't write for theme, but if you work closely on some guy fixing a sandwich or a window or a table or trying to visit an old teacher or walking down the street on which he was a boy, a theme, a human hope, will emerge.