Blame and your self

'Don't blame yourself' or 'blame yourself' are messages to give to different people in different circumstances. Usually, because of how conscience works, those who have overactive conscience should be told not to blame themselves that much and on the contrary individuals who have underactive consciences should be stimulated to blame themselves more, or maybe more positively put, to explore how their role is in what happens with or around them.
It's difficult when you follow rules of behaviour and they don't work out with al people or all circumstances. When do you follow rules and why?