When one does work, one should have a healthy mix of Divergent and Convergent thinking.
Divergent thinking is creative and exploratory -- devising all the possible solutions to a given question. Convergent thinking is the opposite -- applying filters, whittling, resolving issues. Quality work relies on a good mix of both at the same time. Be creative enough to conjure multiple good ideas, but stringent enough to find the ideal fit with your problem.
If you've spent too much time engaging convergent thought, you lose the ability to apply decisive judgment, and every solution can look equally enticing. Whatever the form of work you output looks equally feasible. Dangerously, this diminishes the challenge. And when the challenge goes -- that unknown probability of success that makes our hairs stand on end -- so does your willpower. (Dopamine hits us harder when we think we've an uncertain chance of getting a reward, versus when we know for sure.
http://youtu.be/hrCVu25wQ5s)
As a workaround, spend time doing a mundane activity. Follow a script or do mindless task. Working within a fixed framework such as moving numbers in an excel sheet, filling out forms, or assembling parts, activates a part of your brain dedicated to action and efficiency. You become focused on the most effective way of achieving an outcome, and the sequence of steps necessary to get there -- helping you to Converge upon an ultimate, optimal outcome.
With your Convergence muscle flexed, proceed with initial task.
As for the other way around, Divergence can be exercised through the arts. Dance improvisation, for example, increases our ability at Divergent thinking. (Be careful of ballet though -- its structured exercises incite quite the opposite.
http://www.guardian.co.uk/technology/2011/jul/31/peter-lovatt-dance-problem-solving) Watching a modern dance piece, listening to a concerto, or staring at a painting, introduce your mind to a wealth of unexpected connections. You never realized steps could be combined that way, that those sounds could be combined, that those strokes could juxtapose -- and the inspiration makes you draw connections of your own, outward to a more expansive and Diverse space and set of possibilities.
A good mix of these activities should help you tackle inspiration, and throttle your mystical muse to work to your good. Inspiration can be engineered, and we don't have to wait for the right moment to strike.
(..Just personal hack-patches for the frequent times I'm stuck at work. Like right now, which is why I wrote this as an enabler to crafting a proposal)