I believe that we choose to come to this reality from another reality like for example how we are on the verge of creating totally immersive virtual realities of our own.. I think the experiences we have here in this reality can enable us to create a personality but at everyones core is pure positive energy and the ageing process we experience is baggage that in a way blocks that stream of pure positive energy enabling diseases to manifest etc.. I think the reason for going to a different self created reality could be to help us expand in a safe environment like for example how we dream to experience things we might not want to experience in our actual lives.. ?