Just to qualify this further - what if you're not selling a service on top of your blog? (i.e. design services in your case) - could you still create a labor of love, like a blog and pay rent with the cash it generates? how?
If you think about the end result (pay rent in your case) then you maynot be able to succeed! Okay I don't want to talk philosophy here buy you got the point, didn't you?