This happens to me too. The following have helped:
Go for a walk. I use the alarm on my cell phone and walk "out" for 15 minutes, then walk back home for 15 minutes.
Browse through (quilt :-D ) books or magazines at home or at the library.
Set a timer for 30 minutes and clean, straighten or sort something.
Meet a friend for coffee, tea, lunch, walking.
Get out the colored pencils and paper and design a quilt, draw or just doodle.