Who are you? Caitanya Mahaprabhu taught that we are spirit souls and eternal servants of Sri Krishna and who are we serving. We are mainly serving our tongue and family members which is not our eternal service. This is caused by the illusory energy of Sri Krishna, Maya. We think we are these bodies which is likened to a dream. When we sleep our external bodily activities are suspended and our mental body operates and when our sleep breaks then we realise that it was only a dream. Death is the same when our soul leaves this material body, we would not remember who was my mother or father or daughter etc just like the dream. Therefore, we must give up this dream state by reconditioning yourself to know that you are not this body and that happiness is not possible in this material body and that is the basic teaching of Sri Krishna in Bhagavad Gita.