What are the unpleasant aspects of the human condition that the poet wants to escape from?

While the poet is celebrating his new found happiness in the nightingale's song, he is thrown into much deeper thought. Keats commiserates with the human for the sorrow and all the unpleasantness that one has to go through in one's life. The poet wishes to escape from all these. He wishes to fly away to the bird and drown himself in the ecstasy of its humming. Keats realises the truth of human life. He renounces and learn that this world can serve nothing more than momentary pleasures to humans and rest all is sham and has pain. All the materialistic gains have pain rooted in them and he wants to break free from them. He lists out various such intricacies and obstacles. He tells the bird, who has never experienced fever, weariness, fret; who never sits like men and groans while palsy shakes a few, those sad folks with those last few gray hair. How youth fades and grows pale, thin and dies with time.  He grieves for this world where nothing is permanent. The poet wishes to escape from all these aspects of our physical world and wants to see the other world where true happiness lies, where the spiritual bliss awaits him.