Gary has a great way of articulating how I have made a business out of my blog and the reason it works.
As always, his bottom line: passion.
You can’t blog as a career unless you are truly passionate about your message. People on the web are savvy, and if you have to fake it, you’ll fail. Not to mention, the amount of time, effort, and personal exposure you dedicate to it is a 24 hour job. There is no 9-5 in the blogosphere.