I think this is often true, but not always. You may be having a perfectly good day and then suddenly find yourself in a hellish situation. Learning to detach yourself and observe, goes along way to maintaining a peaceful existence.
Yes! You have to be willing to learn form your mistakes. If you just accept things the way they happen you won't have very good perseverance for when something more challenging comes along the way. Also I strongly believe that things happen for a reason.