How Long Does It Take to Form Habit?

When you have one habit of, say, waking up first thing in the morning and exercising, it has a ripple effect to many other areas of your life. We know that exercise, particularly daily exercise, has a major impact on things like mood, cognition, memory and having more energy. So i won't define for you what that keystone habit should be, but i will challenge you to think about it. Is there one thing in your life that you could focus on and make it a habit so that you are committed to doing it day and day out? Something simple? Does it will be to your detriment to have it be complicated, but something very simple. This is my habit.