Creating a new habit can take anywhere between 18 and 254 days. Based on a study conducted by Phillippa Lally, a health psychology researcher at University College London, published in the European Journal of Social Psychology, it takes two to eight months before a person can form a habit and automatically do something. Forming a new habit depends on the person, his behavior and his circumstances.
In 1960, Dr. Maxwell Maltz, a plastic surgeon, published his thoughts on behavioral changes in the book "Psycho-Cybernetics." In the book, he explained that it takes a minimum of 21 days to create a new habit. This observation was based on his experience, and not on clinical experiments. The book was an instant hit, and many people noted 21 days instead of a minimum of 21 days to form a new habit. This started the myth that it takes 21 days to form a habit.
Mr. Lally and Dr. Maltz both agree that while it may take longer than two weeks to form a new habit, it is possible. Practice makes perfect, so the more a person repeats a behavior, the sooner it becomes instinctive or automatic. Forming a new habit is a process and it should be a goal. Create one habit at a time, and plan specific steps on how to consistently achieve that goal on a daily basis.