#screenwriting #filmmaking #writing #screenplay
Detailed outlining of each and every story before actually writing it in Final Draft will help you answer this.
If a story stops inspiring you, then you might want to drop it or put it aside.
If however you keep doing this and have more than a few unfinished stories lying around, then that's a problem. Then you might need to set yourself the target of always finishing. Which may help you solve the real problem, like perhaps not knowing how to finish.
Read the 2000+ stage Hero's Journey/Transformation/New World, which you can purchase from http://www.clickok.co.uk/index4.html