What type of essay are you writing? Are you supposed to provide examples that support Wiener's suggestion? Are you supposed to take a position agreeing or disagreeing with his statement and support your position?
If you are to illustrate the connection between happiness and geographic location, your essay theme could be a statement regarding how people's attitudes are impacted by where they live. You could use examples from literature to show characters who lived full and happy lives in wonderful locations; you could even include characters who were very involved and greatly enjoying living in physically challenging locations - think about mountain climbers, survivors of terrific storms, etc.
If you are to debate the statement, decide if you agree or disagree with Wiener's idea and why you feel the way you do. Then gather your examples to support whichever side you are arguing. Your theme could be as simple as stating "There is (or is not) a connection between happiness and geographic location," although something more attention-getting and appealing would probably be better received by your instructor.