Not that I've had any, but there's been a couple of posts recently about what makes a blog successful. Jeff Atwood insists it's persistence that makes your blog successful. Scott Mitchell followed with a post with some other tips on successful blogging.
I think both have forgot one very important thing. You can't sleep. I swear some of the blogs that I read have posts coming at 2 in the morning. And those successful bloggers that I follow on Twitter, like Scoble, Dave Winer, Hanselman, are twittering well into the early morning.
It really comes down to what you love to do. If you love to do it, you'll stick with it, you won't sleep, and ultimately be successful at it.