In today's society, people are monitoring and collecting data related to themselves. As people with the help of various applications dutifully record their daily lives, they allow companies to use their data for marketing and surveillance purposes. The paper first looks at the psychological mechanisms that are behind the desire for self-monitoring. Second, it looks at the way corporations exploit these desires. And third, it addresses the question of why people often ignore the fact that data that is collected about their lives can easily be used to their disadvantage.