It’s one of those things we do dozen times a day and don’t even think twice about it: Thank someone. For bagging our groceries. Or holding the door. Or letting us proceed at a crosswalk. But sometimes a simple thank you isn’t enough. 

How do you thank a friend who talks you through a really rough night? Or a sibling who takes care of you while you are going through chemotherapy? Why do we have the urge to thank people for things they have done? And how do we say thank you when "thank you" isn’t enough? 

Robin Abrahams, our social etiquette and human behavior expert. Writes the "Miss Conduct" column and blog for The Boston Globe