Some lessons in life come easy but most occur during mistakes. Mistakes that come with consequences. That is why making small mistakes with non life threatening consequences early in life yields dividends for the remaining time. Just think back to any injury, sickness or emotional pain. Usually that was a consequence of a mistake or poor judgement. From childhood -touching a hot pan on the stove - to adult - lifting a 440lb drum of liquid from upper body, the physical consequences help etch into one's memory the life lesson. Pain punctuates the lesson.
Every person you see is a vessel of lessons that they have conquered. Their stories could help you avoid the pain if you are willing to believe their life lesson. Yet too often each of us must learn our own lessons in life. We learn best when we experience it directly - even with the pain.
Yet our human body was designed to heal and forget pain (just try to remember the extreme pain of a past injury). The consequence fades and often we forget (or ignore) the lesson. That is our human condition - it looks stupid but it happens.
It is why history will always repeat.