Meditations 6.30:

“Take Antoninus as your model, always. His energy in doing what was rational … his steadiness in any situation … his sense of reverence … his calm expression … his gentleness … his modesty … his eagerness to grasp things. And how he never let things go before he was sure he had examined them thoroughly, understood them perfectly … the way he put up with unfair criticism, without returning it … how he couldn’t be hurried … how he wouldn’t listen to informers … how reliable he was as a judge of character, and of actions … not prone to backbiting, or cowardice, or jealousy, or empty rhetoric … content with the basics—in living quarters, bedding, clothes, food, servants … how hard he worked, how much he put up with … his ability to work straight through till dusk—because of his simple diet (he didn’t even need to relieve himself, except at set times) … his constancy and reliability as a friend … his tolerance of people who openly questioned his views and his delight at seeing his ideas improved on … his piety—without a trace of superstition …

So that when your time comes, your conscience will be as clear as his.”

Whether Antoninus (Marcus’s predecessor as emperor) was really this together or not, this description provides a great model of character for anyone to aspire to.