Going through the motions

Lately it has felt  like the wind is out of my sails.  I'm still here, working same hours, appearing to put in the same effort, and still getting acceptable results, but I feel like I just don't have the same passion behind it.  I almost feel like a cubicle monkey today, which is very unusual for me.  I can usually find inspiration in the academic lifestyle, but lately I just can't seem to find the motivation to push beyond the merely acceptable.  I keep going through the motions hoping something will click into place but so far nothing has worked.  I've tried spending extra time in the greenhouse the last few days hoping the positive energy of the green plants would do the trick but today I'm stuck again without feeling the inspiration needed to make something exceptional happen.