Life does not go as expect. There are always detours and challenges that get in the way of goals. Ray Dalio’s book “Principles”, is correct in that most of these challenges happen over and over in one’s lifetime and definitely throughout human history. If you develop principles for dealing with challenges then you will be able to get over them much quicker and with less pain.
You can develop your own principles or adopt other people’s who may have been through a challenge you are going through currently. One of Ray’s biggest principles is Pain + Reflection = Progress. When you fail it causes pain and then you reflect on this pain and wonder how you can do things different then try again.