The author has used a single .txt file as their productivity system for 14 years, relying on a daily routine of copying the next day's calendar items to the file and using it to track tasks, notes, and meetings. This system has allowed them to maintain a record of everything they have done and when, and has scaled with their growing responsibilities. The author finds this system to be practical and flexible, despite its simplicity. They also use a calendar and a basic email flagging system to support their productivity.