Drifting, without aim or purpose, is the first cause of failure.
Without a plan for your life, it is easier to follow the course of least resistance, to go with the flow, to drift with the current with no particular destination in mind. Having a definite plan for your life greatly simplifies the process of making hundreds of daily decisions that affect your ultimate success. When you know where you want to go, you can quickly decide if your actions are moving you toward your goal or away from it. Without definite, precise goals and a plan for their achievement, each decision must be considered in a vacuum. Definiteness of purpose provides context and allows you to relate specific actions to your overall plan.