Commentary on Meditations: B6:16

There is nothing to value in transpiring like plants or breathing like cattle and wild creatures; nothing in taking the stamp of sense impressions or jerking to the puppet-strings of impulse; nothing in herding together or taking food - this last is no better than voiding the wastes of that food. What, then, is to be valued? Applause? No. Not therefore the applause of tongues either: the praise of the masses is the mere rattle of tongues. So you have jettisoned trivial glory too. What remains to be valued? To my mind, it is to act or refrain from action according to our own proper constitution, something to which skills and crafts show the way. Every craft seeks to make its product suit the purpose for which it is produced: this is the aim of the gardener, the vine-dresser, the breaker of horses, the dogtrainer. And what is the end to which the training of children and their teaching strives?

So this is the true value: and if this is firmly held, you will not be set on acquiring any of the other things for yourself. Will you not then cease to value much else besides? Otherwise you will not be free or self-sufficient or devoid of passion: you will need to be envious and jealous, to suspect those who have the power to deprive you of these things, and to intrigue against people who possess what you value. In short, anyone who feels the need of any of these things is necessarily sullied, and what is more he will often be driven to blame the gods too. But reverence of your own mind and the value you give to it will make you acceptable to yourself, in harmony with your fellows, and consonant with the gods - that is, praising all that they assign and have disposed.

Marcus reviews what plants, animals and birds focus on: survival.  Then he reviews what humans will often seek: acting on impulse, eating, defecating, applause of hands and tongues.  All of these things he has learned to scorn.  Now he must focus on acting with reason.

He must ignore all that and hold in reverence his mind - his ability and capacity to think and reason.  He must act in harmony with other people, and accept and love all that the gods (universe) has dealt him.