When the sense or feeling 'I am' appeared on you it duped you into believing that you are the body, and later on that you are so-and-so. It strengthened the illusion all the more as time went by and thus began all the turmoil and suffering, in this sense it is your foe. But now the Guru tells you to come back to the 'I am', understand it, stay there, make friends with it or rather make it your guide, God or Guru. Doing so the 'I am' shall help you break the illusion and it will itself lead you to the source.