Sendhil Mullainathan is Professor of Economics at Harvard University. His real passion is behavioral economics, understanding what makes people tick - whether a senior executive in New York or a farmer in rural Tamil Nadu. He enjoys having written but is of a mixed mind about writing. He also occasionally enjoys doing: he helped co-found a non-profit to apply behavioral science (ideas42); and has worked in government. Much to the surprise of who know him well, he is a recipient of the MacArthur "genius" award. His hobbies include basketball, googling and fixing-up classic espresso machines. He also enjoys speaking about himself in the third person, which works well for bios but less well in daily life.