Whereas I have no ambitions to write a book, the idea of writing every day simply as a tool to inspire creativity and keeping your mind active is very appealing!
As a writer, I'm sure you're familiar with Julia Cameron's "The Artists Way" series, which also advocates writing every day, "whether you feel like it or not."
The creative flow definitely does come more smoothly when you make something "a practice."
=^..^=
And daily practice builds the habit. Then soon it's incorporated into your very being :)