Keats' theme

Hi there, I am currently doing a literature course at school, and we were recently given an assignment on John Keats. It asks me to write an essay on the following:

"While many of Keats' poems, not surprisingly, deal with themes of death and dying, his poetry can be read as an affirmation of life rather than a morbid reflection on mortality. Discuss with reference to Keats' poetry."

Any ideas? Preferably, I would like to see references to "To Autumn", "Ode on a Grecian Urn", "Ode on Melancholy" and "La Belle Dame Sans Merci".

Thanks in advance :)