You sit by the computer, you go to the grocery store, to the post office, the library. You come back and stare and stare at the computer again. There is nothing. You don't have a single idea.
You long to post a new hub, a lens, a post to Yahoo Contributor Network. You sit until sweat pours from your brain and drips onto those still fingers placed upon your keyboard.
You know this is terminal. A terminal case of writer's block.
The more you try to think, the more coffee you drink, the more the cursor winks.
Ah! The muse has struck. :)