Premanand Maharaj Ji
Why is thinking 'I am the doer' called ego, and what ends it?
Ego is believing you are the doer
Saying 'I did this, I will do that' is ego, and surrender of it is bhakti. Even good deeds like feeding saints lose their merit if you puff up with pride about them.
Bhagwan has said in the Gita: the one deluded by ego thinks 'I am the doer'. The ignorant person considers himself the doer.