As serendipity would have it, I started to read a collection of writings by Ann Patchett called This is the Story of a Happy Marriage. It is a series of magazine articles she wrote over a number of years which she put in an anthology of writing and what I found fascinating was her first number of chapters about the art of writing. If you are interested in writing, you have to read the first few articles or chapters in her book where she talks about the art and science of writing and definitely calls it hard work. Everyone does not have to write in the same way on the same day and there are lots of ways of approaching writing but it is definitely not something that just pours out of you, she says. It is a craft that has to be learned and honed she insists. Everyone does NOT have a book in them, just as everyone cannot be a composer, for example or a proficient flower arranger.
If you are even considering writing a book, do yourself a huge favour and read the first few articles she wrote about the craft of writing!