“On average, it takes more than 2 months before a new behavior becomes automatic — 66 days to be exact. And how long it takes a new habit to form can vary widely depending on the behavior, the person, and the circumstances. In Lally’s study, it took anywhere from 18 days to 254 days for people to form a new habit.”

James Clear debunks the 21 day rule in this article outlining how to form or break a habit.

how to form or break a habit