Eight hours in the writing position

My friend Rory Green (doesn't she have a great name?) shot me a twitter message with a link to this video. It got lost in the land of direct messages for a while (ie: I didn't check them), and I finally watched it today. Thank you so much for sending it, Rory. Just seeing long-legged Lyle Lovett is enough of a treat, but to hear Dave Eggers talk about the writing process is like stumbling headlong into a cool stream in the middle of a parched dessert. After spending eight hours in the writing position today and accomplishing about 45 minutes of actual work, I was grateful for someone who could at least partially explain why. 

And, then, for Jonah Lehrer to talk about grit, persistence, stubbornness, sadness--wow. 

If you're a writer or other creative artist, what do you think? Do you find you become more focused and persistent in your work when you're sad? Do you think you can use your persistence and stubbornness in your favor? What can we do to better harness that energy, that grit?

I look forward to seeing you in the comments.