History is critical for depth in a good epic fantasy novel (the Lord of the Rings being an excellent example), but sitting down to write a whole history like the Silmarillion is daunting. :)
But, I've learned I don't have to do that. I can take a character or a place, say the cliff city of Underrim, and write a short narrative history of it. That's a lot easier than trying to write the history of a whole world: the back story of a city or a person is a much smaller task.
How do I write the back story? To a certain degree, it's like a logic slider: I can look at the political and cultural state in which I want Underrim, and figure out a chain of events that would have taken it to that point (which is a lot of fun). And if I find inconsistencies in back stories, it's really an opportunity to create even more interesting story. :)
I then have something to write -to- in my novel. I know how the city got to where it is, and I know something more about the city than when I started. As a consequence, I can work better texture into my story.
I've liked history for my stories all along, what I've learned is how easy it is to do in bite-sized chunks. (But I still have histories of my whole fantasy worlds in mind, if only as overviews. :)