Problems with taking actions

So its been almost 2 years now since I discovered the fact that I want to make movies and create great stories that have an impact on the viewers. I started watching a whole lot more movies (currently over 500 on my watchlist) and reading some Books (finished Syd Field's Screenplay, Robert McKee's Story and recently John Truby's Anatomy of Story) and screenplays of movies that I find fascinating. But it turns out that I have difficult time starting my own scripts. I have some ideas and I know I should "just write" and the first drafts will be worst that I could imagine, but the question I have for you guys is: What have you done/ would you do to overcome this phase?

P.s.: its my first post so feel free to correct or advise me if I did something wrong by posting this.

Thanks a bunch, David