One way to have a plan in your mind to do something is to brainstorm and organize your thoughts. This involves thinking about the desired outcome, breaking it down into smaller steps, and considering any potential obstacles or challenges that may arise. Additionally, setting specific goals and deadlines can help in creating a clear plan of action. It is also important to consider resources and support that may be needed to accomplish the plan. Regularly reviewing and adjusting the plan as necessary is crucial for its successful implementation.