When that happens to me I shift into another mode: designing or reworking or rewording a pattern. I might strongly encourage myself do a very small project, even if it is mending a shirt. I relax.
Usually there is a reason. When I force myself I find I am more dissatisfied with my finished product.
When I do this gentle pondering I often later realize what it was that was 'bothering/blocking' me. It might be the fabric I chose. it might be I didn't like the directions given. Or even that I wanted to think more about the borders or actual quilting.
The fabric I wanted to use in the OBW. I couldn't make myself work with it. It turned out it reminded me of some not so pleasant things - sick baby poop or bile. It made a beautiful fabric bowl, which I quickly finished and gave away as a gift to a friend.
I figure if my best friend wouldn't beat me up about my dithering, then why should I.
ali