With regard to Stoic philosophy, Marcus mainly focused his self-improvement efforts in "Meditations" on virtue, nature, reason, and what is in our control vs. isn't. As an emperor fighting in war and experiencing death daily, he needed a way to understand the world around him, so he took to journaling. Although Marcus was an emperor, he still was humble to the fact that everyone is subject to the same universal laws and fate.
"In the morning when thou findest thyself unwilling to rise, consider with thyself presently, it is to go about a man's work that I am stirred up. Am I then yet unwilling to go about that, for which I myself was born and brought forth into this world?" — Meditations: Book 5, Verse 1
