I clean and re-organize my sewing space. I'm talking removing just about all the contents, and starting over. Typically by the time I'm done I am highly motivated to do just about anything other than clean and organize. If that doesn't do it for me .. at least I have a clean space once the "mood" changes. Many times I just don't feel like sitting .. and the cleaning is the active moving part I am looking for.
Should yours space be tidy ... do go for walks as suggested, excersize is the best for altering a mood.