I have made my living as an Agile coach since 2003. I have worked as a coach for clients around the world, taught many courses in various topics, and spoken at too many conferences to count. I have dedicated more than a third of my life to these concepts and truly believe they have been the best way to deliver software.
Agile has gone through many changes over my career. A few of the major ones that I feel have had the most impact are the introduction of Lean Startup, practices like BDD and Acceptance Test Driven Development, and my favourite which is Continuous Delivery. Most of these changes have come from within the Agile community and have pushed us forward in our understanding of how to deliver more value quicker. I have stayed current and in some cases have been on the forefront for many of these changes.