Peter Elbow http://en.wikipedia.org/wiki/Peter_Elbow recommends freewriting for ten minutes at least three times a week. http://mgunby.wikispaces.com/file/view/Freewriting.pdf
The exercise consists of writing non-stop, whether you're in the mood or not, for ten or fifteen or twenty minutes, without editing or rewriting, whatever you want. The purpose is to limber up your mind, find your voice, force and connectedness, which will eventually carry over into your focussed writing.
Can I spare thirty minutes per week to improve my writing? It sounds to me like my time will be well spent and I have nothing to lose considering it's only half an hour. Maybe my mind can benefit from daydreaming on paper.