It simply means not being answerable to anyone but to yourself and only to your God.
I am responsible for my thoughts, my actions and feelings. Whenever I feel happy or in a state of bliss, that is mine alone. No one can even imagine what sensations, what music the heart hears. Similarly, when the agitations start and pain becomes unbearable to the point of giving up, no one can feel it as deeply as I do let alone pretend to understand what that is. Feelings don't require understanding, it is just 'felt'.
My pain just like my happiness belongs only to me and to no one else. Everyone has their own set of emotions, distinct and separate from each other. While we can only empathize or sympathize with one another, at the end of the day we do not know exactly what one feels. There is only a certain point that you can allow anyone to get near to what you are experiencing at the moment but no way can anyone breach that line. Even if you say 'oh I'm so happy!' or 'hey, I feel so low' that is just a mild description of what is really going on inside. No on really has an idea how your happiness or your heartache feels. That is simply your own and you don't owe anyone an explanation..
