If you have a plan you’re more likely to accomplish a goal. No matter what the goal is, big or small, a plan will give you an overview of what needs to be done from start to finish and clarify for you the next step you need to take at each and every moment along the way.
A well thought out and written plan will help you to execute.
Any project you have (a project loosely defined as a meaningful goal that would take more than one step to complete) should have a plan.
As the famous quote goes, if you fail to plan your plan is to fail.