This document outlines 15 lessons learned as a product manager. Some key lessons include: focus on increasing revenues and reducing costs while delivering value for today's costs; understand customer and market needs through quantitative and qualitative data balanced with intuition; set realistic expectations and don't push unrealistic quarterly targets; test hypotheses early to fail fast; and serve as the owner and conduit of information between cross-functional teams to drive the product vision while remaining unbiased. The overall message is the importance of balancing strategic and tactical work with a focus on building products customers love.