Back when I was actually writing stories, I would always get stuck after the beginning. Always wondering where to go next. And I never had any sort of idea of how I wanted to END my story. Through a lot of trial and error and trying out different ways to plot stuff out, I found that when I had a really developed ending in mine. Scenes and everything. it was A LOT easier to fill in the blanks of the middle-part to help accomplish that.
For a long time I refused to put any of my story ideas on paper because I didn't think it would be any good. Even if I'm not going to let more than one or two people read something I write, it just feels good to have it out of your head and on something tangible.