Summary of doctoral thesis: My thesis studies Stoicism and Epicureanism as ways of life, and the way that these philosophies play out in the practitioner's experience. I take an interdisciplinary approach to the topic, employing Heidegger's philosophy as a methodological basis and treating the ancient ethical question "how should one live?" as a variation of the question fo Being. My thesis seeks to discern in the practitioner's experience the fundamental existential attitudes that underlie Stoicism and Epicureanism and turn these philosophies into coherent ways of being and living in the world.