psychologically, it is esteem (specifically, achievements, respect by others ) that motivates you, referring to Maslow's hierarchy of needs http://en.wikipedia.org/wiki/Maslow%27s_hierarchy_of_needs Sigmund Freud said that everything you and I do springs from two motives, and one of the motive is the desire to be great. when you contribute/achieve something, something can be as small as cooking for your family, something can be as substantial as being a champion in Olympic, you feel great, because you get self-actualization, or your self- esteem is gratified. in some circumstance, for instance, you just buy a luxury that lots of your friend cannot afford, your friends admire/envy you, you have the attention, you feel wonderful, I think this time the vanity is gratified. sorry no Chinese input here.