I wish I had discovered Marcus Aurelius years ago. I would have had a much different life.
"Meditations" has definitely changed my life. I have learned to be more patient and to not let the small things bother me. I have also learned to be more mindful and to live in the present. And also how to effectively rule a global empire.
For those who like fictions set in antiquity in the first person, I can highly recommend Marguerite Yourcenar's "Mémoires d'Hadrien" (1951, engl. transl.: "Memoirs of Hadrian ").