As a child, and I suppose as an adult as well, daydreaming is kind of frowned upon. It is a sign of being frivolous and it is encouraged that one is always firmly set in this world. Well, I never got that. This world can be pretty boring, or annoying, or stressful. There are so many other worlds that are for more interesting, which is also why we turn to books.
Not only that, but daydreaming has always been the first step of writing a novel for me. It is very rare that a character just stumbles into my mind. Usually I have to crack open the door first. Some people also get inspired by actual dreams, which I think is amazing and only happened to me once. Most of the time when I’m working on a novel it helps to take a while and lie on bed or sit on the sofa and daydream about the next events and usually all I have to do is write them down next. It helps to work out possible problems (plotholes, for example) in advance, as well.
If you’re a writer, and even if your not, it’s good to daydream because it restores brain cells. So next time somebody comments on your daydreaming, inform them that you’re restoring your brain and plotting your novel at the same time. And if they’re not careful, they might end up as a victim in your book.