How is life like a "classroom"? Think of a time in your own life where you learned something from life instead of in a classroom

This question calls for your personal experience, there is no right or wrong answer. Life serves as a classroom in numerous ways. Think about your friendships.... what have you learning about true friendship over the course of your life? Have you ever done something that held negative repurcussions? Would you do it again, or did you learn a lesson from it..... would you do it differently?