This document discusses how data-driven digital services can win customers' hearts by maximizing their emotional rewards and saving their time. It explains that personalization provides customers the most desired content, directly optimizing emotional reward while also minimizing effort through easier navigation and search. This maximizes customers' reward-to-effort ratio and creates addictive user experiences that attract more users who spend more time, maximizing a business's total value. Data science and personalization will be inseparable from digital services and business success in the future.