1| Sometimes you are talking to yourself.
Sometimes people don't read your blog. Sometimes the blog post you send out isn't really worth reading. (But everyone needs a post that just gets them back in the habit here and there right?) And those times mean that your blog post is basically the written equivalent of you talking to yourself.
2| You take pictures of everything.
Because there is the teeny tiny small chance that you just might use it for a blog post.
3| You stress about the exact timing of when your posts/tweets will go out.
That idea that randomly popped into your head at 2:30 in the morning probably isn't going to be seen if you decide to post it right then. But when will it be seen?
4| You obsess about other blogs.
Reading blogs. Commenting on blogs. What are those bloggers doing? On their blogs. On Facebook. On Twitter. On sponsorships.
5| In general, blogging is just plain obsessive.