Esther Derby finds inspiration for mental blocks from Ursula LeGuin:

When action grows unprofitable, gather information. When information grows unprofitable, sleep.

By the way: Esther's blog is a good source for opinions and discussion about the human side of work. For example:

• How to ask for help
• You really can't do more with less
• What project managers do
• Advice on writing

If you are a manager, or just an engineer dealing with people stuff, take a spin around Esther's blog: it couldn't hurt!