Ivaankov notices that Sanji sustained many injuries he could have avoided if he truly valued himself or loved himself, and that this is his greatest weakness.
Sanji reflects on Ivaankov's words, and accepts himself after realizing that being a member of the Straw Hat Pirates gives him a reason to love himself and gives his self value.
We also discover that the idea of overcoming fears erases the existence of the nightmare embodied in front of you.