The Power Of Habit

by CHARLES DUHIGG

She was the scientists’ favorite study participant. Lisa Allen, according to her fi le, was thirty- four years old, had started smoking and drinking when she was sixteen, and had strug gled with obesity for most of her life. At one point, in her mid twenties, collection agencies were hounding her to recover more than $10,000 in debts. An old résumé listed her longest job as last ing less than a year.