(1) It may be a true inner voice telling you what you must do in order to stay in tune - or to get in tune - with your ‘destiny’ (what Indians call ‘dharma\ a word which means both ‘destiny5 and ‘duty5).
(2) It may be a pontification from an over-developed super-ego, reflecting either irrational fears or guilt-feelings stemming from traumatic childhood experiences, or conventional notions of right and wrong instilled into you by parents or accepted from other people unconsciously or in an anxious effort to conform. In the former case there will invariably be something compulsive in your behaviour, something that will indicate that what is controlling your life is not reason but (unconscious) emotion. In the latter case consider: no one and nothing has any authority over you unless you give them it; you alone are responsible for your decisions and values; and your essential duty is to your inner self. [1]