The great thing about writing is that there are literally no rules. Write down your grocery list, your to-do list, your dream record collection. Write about the friend you saw today, or the interaction you had with the grey little deli cat. Write about the pained feeling of regret you felt that Sunday morning, when the rain was falling down outside your window, and you longed for a version of yourself that was never able to exist. Write about the time you went to Aldis, there's no boundaries!