Writing and rewriting phases allow you to implement your planning and the results of your experimentation while prewriting. You implement your strategy, working out the details and fine-tuning your thoughts. In the rewriting, or revising, phase, you review what you have written and consider how and where your writing can be improved.
It’s important to remember that there is no such thing as a perfect writing process, and you can always edit and polish your thoughts later. Being passionate about your chosen topic can also help motivate you to get started. Write. Generate ideas. Revise later. Try to have fun with it!