What is the battle fought by every artist. I would hazard a stab at the old enemy procrastination. I would also include cluttered thoughts to the list. The muse visits when the mind is uncluttered and clutter stems from a cluttered life. Or in this case a cluttered studio. There is no doubt that clearing out physical clutter frees the mind as well. Try it for yourself and do not put it off. It is a liberating experience.
My studio got to the point where I would bump into things on the floor, books piled up haphazardly and old, abandoned paintings stacked up against the wall. All of this irritated me and that interfered with my focus on the easel. Once the penny dropped it was clear that something drastic had to be done. Clear out everything not useful. No not perhaps useful one day. Everything that I would not use this week, if I needed to, had to get binned! Typical examples: paintbrushes that have been worn down; dirty, unused jars, cans, paint tubes untouched for months, painting panels waiting "to be finished", magazines (where do they all come from!) papers, receipts and so on. Do not even think of dissecting art magazines for useful pics for a scrapbook. It is a delusion! Chuck it out.
What about half finished paintings abandoned with the hope of a miraculous revelation leading to completion. Burn them! There is a reason for them not being completed - you were on the wrong path and your muse has shown you a better way. IT HURTS BUT YOU WILL PAINT BETTER PAINTINGS!
The result of this process (for it is a process not just a once off event) was an immediate lightening of my mood and two great paintings were completed shortly thereafter.