Another one here who has two reading speeds. Non-fiction and badly written histories just drag along. With fiction, I pretty much enter a fugue state and
lose track of the world around me. I'm one of those people who's got his nose buried in a book while walking down the street. And I get seriously annoyed at anyone who interrupts me while I'm reading ...
As for getting to that point, I think it's something kids absorb from their parents. It was never shoved onto me, but both my parents were readers, so I grew up seeing that as the norm, not the exception. And make sure there's something interesting available (my first "real" book (no pictures) was Edgar Rice Burroughs!)