Ok, here's a question to think about.
There is a man who lives in a 20 story apartment building. He lives on the 17th floor.
Every morning he leaves his apartment and rides the elevator to the lobby and goes to work.
Every evening he returns to his building and rides the elevator to the 14th floor. From there he climbs the stairs to his apartment.
He does this every day, whether he feels like it or not.
Why?