When you finally realize that all mistakes are lessons, when you reflect back on your life you will understand that there was a good in all the crap you went through. For example, if you had a parent who neglected you, you tell yourself, I will be a good parent to mine. I will never let my kids feel the loneliness, the abandonment I felt as a child. You take the bad in your life and your turn it into positive. A bad wife or husband, teaches you in your future what you wont tolerate in the next relationship. A demanding mean boss who overworks you teaches you to find a better understanding boss and a better job the next time. Find the bad and turn it into good.
Although, maybe we’re not always ready to learn each lesson when it presents itself. Sometimes the same lesson might need to come round more than once before we fully take it in.