Pre-contemplation, planning, action, maintenance-habit.

Pre-contemplation, contemplation, planning, action, maintenance-habit. How long does it take a habit to form? I feel I often am stuck at the stage of planning. The planning rarely leads to action, which scarcely leads to the maintenance of that action and forming habit. I've always admired and had extreme respect for the people who have mastered the art of time management and are people of habit.