When you make your bed each day, you embody the identity of an organized person. When you write each day, you embody the identity of a creative person. When you train each day, you embody the identity of an athletic person.

The more you repeat a behavior, the more you reinforce the identity associated with that behavior. In fact, the word identity was originally derived from the Latin words essentitas, which means being, and, identidem, which means repeatedly. Your identity is literally your “repeated beingness.”

Whatever your identity is right now, you only believe it because you have proof of it. If you go to church every Sunday for twenty years, you have evidence that you are religious. If you study biology for one hour every night, you have evidence that you are studious. If you go to the gym even when it’s snowing, you have evidence that you are committed to fitness. The more evidence you have for a belief, the more strongly you will believe it. 

Clear points out that focusing on the type of person you wish to become can be a powerful tool for changing your habits.