The War of Art, Steven Pressfield

On my "to read" list. Check out an excerpt here.

A tidbit: 

"Resistance cannot be seen, touched, heard or smelled. But it can be felt. It is experienced as a force field emanating from a work-in-potential. It's a repelling force. It's negative. Its intention is to shove the creator away, distract him, sap his energy, incapacitate him.

If Resistance wins, the work doesn't get written."