When one receives a personal gift or benefit that was not earned, deserved,
or expected, but instead due to the good intentions of another person, a typical
emotional response is gratitude (Emmons & McCullough, 2003). People are
grateful if they are aware of and thankful of the good things that happen to them
and if they express thanks to those responsible (Emmons, 2004). McCullough,
Emmons, and Tsang (2002)