Take a walk somewhere.  Anywhere.  Pay attention to your surroundings.  If you’re anywhere urban, suburban, or otherwise sometimes populated by other humans, look for one sign of another person having been there (who isn’t there now).  Graffiti.  A cross next to a bad turn on a country road.  A hand print on a toy store window.  Anything.  Brainstorm about this person – were they here alone, or with someone?  How were they feeling?  What was their purpose?  What is the rest of their life like?  Free write about it, or if a story just comes to you, start writing it.

If your walk is out in the woods, away from people, turn your attention to evidence of animals.  Prints, scraped bark, old nests from prior years, burrows.  See what’s around.  Write from the animal’s point of view, or if that’s not your cup of tea, think about what kind of character would pay attention to the details you’ve noticed.  A hunter?  A bird-watcher?  A conservation expert?  Someone from the past, who needs to pay attention to the environment around him/her in order to survive?