We wrote two blog posts that you might find useful if you're in this kind of situation:
1. Why you should share your “secret” startup idea with anyone who will listen:
http://www.kilometer.io/blog/why-you-should-share-your-secre...
2. Don’t build anything until you have a clear startup mission
http://www.kilometer.io/blog/dont-build-anything-until-you-h...