How long does it take to build a new habit?

There is nothing magical about time passing with regard to habit formation. It doesn’t matter if it’s been twenty-one days or thirty days or three hundred days. You could do something twice in thirty days, or two hundred times.

It’s the frequency that makes the difference.

Your current habits have been internalized over the course of hundreds, if not thousands, of repetitions. New habits require the same level of frequency.

-Atomic Habits, p.146