Using what you have

I recently read an article written about Joss "Nerd Lord" Whedon where they asked him how he got so much done.
He used a lot of words. He had a lot of advice. It was good.
The gist of what I got out of it was that he knew what he was going to do in general each day, just not in specific. So if he woke up and the calender said write, you wrote something. Maybe not what you meant to write but something. You'll use it later.
I needed to write today. But it was a bad day. Things weren't going right and the scene I wanted to write just wasn't going to happen. Let's face it, I was depressed.
Something in the back of my mind reminded me of the article. Write. Maybe not what you wanted but write anyway.
So I did something very hard. I wrote the hard part of my book.
I'm a fairly easy going person and so most of my stuff comes off light (I hope). But in any book there is the time, as one of my teachers used to tell me, that you have to drown your children. Without something painful your characters don't learn, don't grow, and are really dull, no matter how wonderful they are.
So today I wrote the hard part. I killed my Dumbledore. I threw my Gollum into Mt. Doom. I sacrificed my Obi-Wan Kenobi.
Tomorrow I may regret the way I wrote, I may question the decisions I made or the manner I handled them, but no matter what I will be glad that I went ahead and took on this challenge when I was already in this state of mind.

I couldn't find the exact article (I wish I could) but here was some other advice he had that I'll share.
http://aerogrammestudio.com/2013/03/13/joss-whedons-top-10-writing-tips/