A person realized their passport had expired just before leaving for a trip to Mexico, leading them to renew it immediately. To avoid similar situations in the future, they created a calendar event called "1 year till passport expires" and added tasks like renewing their passport and paying estimated taxes to this calendar. This approach helps by focusing on specific dates, turning tasks into events, building time for the task, and applying to recurring chores, document expirations, and annual activities. The person found that using a calendar is more effective than relying solely on a to-do list, especially for tasks with deadlines or consequences, such as paying taxes or taking care of pets.