Imagine we could go back and tell our past selves something. So we could go back and avoid some mistake we were going to make. We think this is impossible because of the nature of time, only flowing in one direction and all that, but is that the real problem? We cannot listen now to our past selves either, very well. There are certain things we knew as children that we can no longer hear very well. For example, we know as adults that we have lost something, but we can easily attribute that to our superior wisdom as adults, and discount what that child-self knew. If we could really retain that knowledge we would be irritating Peter Pans, always insisting on not losing the magical view of the child. What could be more tiresome and grotesque than that?
The real problem, though, is that we cannot even listen to what our present self is telling us. This present self that could go back and tell the past self what to do, cannot even do this in the present.