9 timeless lessons from the great Roman emperor Marcus Aurelius

"Each of us lives only now, this brief instant. The rest has been lived already, or is impossible to see," Marcus writes.

There is nothing to be gained from letting your mind live separate from where your body finds itself.

The emperor was faced with constant fighting, the rebellion of his general Cassius, the deaths of his wife and close friend, and the realization that his son Commodus was destined to be a bad ruler.

But when he removed his feelings from how he perceived these events, he was able to have empathy for the people who disappointed him and acceptance for the losses that hurt him, since nothing in nature — like death and decay — is evil, he writes.

In recent book "The Obstacle Is the Way," Ryan Holiday cites author Nassim Taleb's definition of a Stoic, which is someone who "transforms fear into prudence, pain into transformation, mistakes into initiation, and desire into undertaking."

As Marcus writes: "Something happens to you. Good. It was meant for you by nature, woven into the pattern from the beginning... Get what you can from the present — thoughtfully, justly."

Marcus writes that people try to retreat from their problems and responsibilities by going somewhere like the mountains or the beach, but that travel isn't necessary to recollect yourself.

He advocates a kind of brief meditation, where you withdraw into yourself and quiet your mind.

If someone's character flaw has caused one of your problems, do not exert energy trying to change that person's character. Let things go.

"You might as well resent a fig tree for secreting juice," Marcus writes.

"Choose not to be harmed — and you won't feel harmed. Don't feel harmed — and you haven't been," Marcus writes.

Similarly, do not let adulation from others overwhelm you.

Do not define yourself by others' perception of you, since the only way someone can truly harm you is if they change your character.

"You could leave life right now," Marcus writes. "Let that determine what you say and think."

He explains that he should not fear death, but be mindful of the impermanence of the human experience. If he overcomes the fear of death, then nothing else should inspire fear within him. That can free him to accomplish what he feels compelled to do.

It also frees him to see people's character more clearly, beyond the values imposed by social structure, since "death and life, success and failure, pain and pleasure, wealth and poverty, all these happen to good and bad alike, and they are neither noble nor shameful — and hence neither good nor bad," he writes.

Marcus regularly ruminates on how an individual's place in the universe is minute, and that even the most celebrated people are washed away by time. When he wonders, then, what the point of it all is, he concludes that it is about a personal journey.

He notes the importance of meditation and reflection, but judges the mark of personal progress to be through action that helps others and in turn connects you more with the human experience. In his final years, he kept reminding himself that he could not afford to slow down.

"Do what nature demands," he writes to himself. "Get a move on — if you have it in you — and don't worry whether anyone will give you credit for it. And don't go expecting Plato's Republic; be satisfied with even the smallest progress, and treat the outcome of it all as unimportant."