In Kurt Vonnegut’s writing on the topic, he identified at least eight common “shapes” for stories, but in the video clip you saw him talking about only three of them. In Christopher Booker’s book, The Seven Basic Plots, he identified seven core plots from epic stories that seem to come up again and again even in modern stories.
To psychologists, it seems fairly obvious that the reason most stories come down to these core plots is that they represent something fundamental about human nature and the way humans overcome obstacles in their lives, even on a small scale.
Review some of the obstacles you’ve face in your own life (large or small), and consider which ones could be expressed in terms of one of Vonnegut’s or Booker’s common “shapes” for stories. Brainstorm a list of ideas that come to you, then pick one to explore further through writing.
Boy Meets Girl: find something wonderful, lose it, get smart and get it back
Cinderella: good person in bad situation encounters a way out and up
Overcoming the Monster: overcoming a threat to you or your loved ones
Rags to Riches: good person in bad situation encounters a way out and up
The Quest: setting out to meet a goal and overcoming obstacles along the way
Voyage and Return: seeking new knowledge or ideas, overcoming obstacles, returning with new insight
Comedy: despite a variety of obstacles, the situation ends happily (you meet your goal)
Tragedy: even if you overcome some obstacles, the situation still ends badly (you don’t meet your goal)
Rebirth: an opportunity to start over as a way of overcoming obstacle in the way of a goal