The Biggest Challenge of Being a Blogger

What is the biggest challenge of being a blogger, dear readers?  Consistently putting out material.  (Nevermind whether or not it's GOOD, meaningful, substantial material.  That's another can of worms in and of itself.)

I remember reading a statistic somewhere about how half the blogs out there on any given day won't be in existence a year from it.  I notice quite a few of the blogs I enjoy and follow haven't updated in quite a while.  I notice there are often longs gaps between updates; I also notice some blogs slowing down in their regularity of updates.

I am curious why this might be - other than the obvious 'life is busy'.  Is that it?  Is it a lack of material?  I feel I have exhausted several subjects I have enjoyed writing about in the past.  Is it a lack of an outside motivating factor?  Since most bloggers' blogging is a self-employed experience - is it that there are no deadlines and little to no consequences for not putting out new material regularly that plagues us?  Now, I've always liked to think that I'm a rather self-motivated person - however, there are several things over the past couple years that I decided, on my own, that I wanted to accomplish.  Not all of these things have been done.  I've been super busy is a good go-to excuse.  

Anyhow.  Do my fellow bloggers agree that this is the biggest challenge?  How do you stay on top of blogging regularly?  What does the rest of the blogging community do to combat these challenges?  Where do my fellow bloggers get their material?  How do you all stay motivated?  Your thoughts?