It is well known that it takes 21 days to build or break a habit. Whether you want to spend one hour a day learning the Korean language (better to transform that plenty of hours of watching k-drama into something useful, right) or to stop drinking coffee, you have to do it for three consecutive weeks. You may skip it one or two days during those three weeks, but more than that will make it difficult to get back on track.
Furthermore, if you keep doing it for the next 69 days after it becomes a habit (total 90 days), the habit will change to a lifestyle. While habit relies on willpower and self-discipline, lifestyle is already embedded in your behavior that you may perform it unconsciously. It requires harder efforts to break a lifestyle than a habit.