This document summarizes 20 lessons learned from the speaker's experience transitioning from UX design to product management and back again. Some of the key lessons include: managing a packed schedule of meetings, learning to use spreadsheets effectively, trusting your gut instincts, choosing battles wisely, always selling ideas to stakeholders, understanding why other roles like designers and developers can be frustrating at times, and maintaining a fun and humble attitude to avoid "asshole syndrome" despite the pressures of the job. The speaker acknowledges the transition requires adapting skills and being open to constant learning.