In man's life his time is a mere instant, his existence a flux, his perception fogged, his whole bodily composition rotting, his mind a whirligig, his fortune unpredictable, his fame unclear. To put it shortly: all things of the body stream away like a river, all things of the mind are dreams and delusion; life is warfare, and a visit in a strange land; the only lasting fame is oblivion. What then can escort us on our way? One thing, and one thing only: philosophy. This consists in keeping the divinity within us inviolate and free from harm, master of pleasure and pain, doing nothing without aim, truth, or integrity, and independent of others' action or failure to act. Further, accepting all that happens and is allotted to it as coming from that other source which is its own origin: and at all times awaiting death with the glad confidence that it is nothing more than the dissolution of the elements of which every living creature is composed. Now if there is nothing fearful for the elements themselves in their constant changing of each into another, why should one look anxiously in prospect at the change and dissolution of them all? This is in accordance with nature: and nothing harmful is in accordance with nature.
Book 2 wraps up with classic Marcus Aurelius. He reminds us that change is the only constant. Our bodies are constantly dying and deteriorating, our minds unfocused, our fortunes and future un-knowable and the ultimate state we will all assume is oblivion.
What can help us in this seemingly chaotic state? Philosophy - "a theory or attitude held by a person or organization that acts as a guiding principle for behavior."
Marcus goes on to counsel himself (and us) that we are keep our mind pure and full of integrity (discipline of assent), doing nothing without a good purpose (discipline of action), and accepting all that is out of our control and for our improvement - whether to help us act better or to help us strengthen our virtue (discipline of desire).
(see also Citadel p. 35, 113, 123, 264)