As humans and effective teachers, we will always regret things - certain choices we made, how we taught a lesson, how we reacted to a student, etc. Not only is that natural, it makes us better educators and people. Learning from mistakes is at the center of any authentic learning. To the narcissistic few that say they have "zero regrets," I'll remind them that no one is perfect. As we learn from the past, it's also important we don't live in the past - or in our regrets. That's a recipe for unhappiness and ineffectiveness in the education profession AND life. Let it go. You deserve it and so do the kids you serve.