I had never heard that before last night, and it was so simply
   said and deep. And it describes many emotions but the best it
   describes is: Envy. "Oh, look at her - she has it all. She has
   good looks, a hardworking husband, beautiful kids, nice clothes,
   nice house (OUTSIDE) and here I am unhappy, miserable, angry all
   the time at everybody for everything (INSIDE)." and its so true:
   You can't compare how you FEEL with the outside APPEARANCES of
   another person. They're totally different. "