Think always of the universe as one living creature, comprising one substance and one soul: how all is absorbed into this one consciousness; how a single impulse governs all its actions; how all things collaborate in all that happens; the very web and mesh of it all.
You are a soul carrying a corpse, as Epictetus used to say.
Change: nothing inherently bad in the process, nothing inherently good in the result.
There is a river of creation, and time is a violent stream. As soon as one thing comes into sight, it is swept past and another is carried down: it too will be taken on its way.
All that happens is as habitual and familiar as roses in spring and fruit in the summer. True too of disease, death, defamation, and conspiracy - and all that delights or gives pain to fools.
What comes after is always in affinity to what went before. Not some simple enumeration of disparate things and a merely necessary sequence, but a rational connection: and just as existing things are harmoniously interconnected, so the processes of becoming exhibit no mere succession, but a wonderfully inherent affinity.
Returning to one of the fundamental principals of Stoicism: there are things in our control and things out of our control. The things that are out of our control should not drive our perception of the world; they should not affect us or our attitude or judgement.
Therefore, one of the exercises of the discipline of assent is to delineate those things that should not affect our attitude and perception of life.
In 40, Marcus recognizes we are part of the vast, complex universe and are subject to the impulse of that magnificent body. Our attitude ought to embrace the impulse of the universe.
In 41, Marcus recognizes that it is our mind that is in control of the body, not the other way around.
In 42, Marcus reminds us that there is nothing good or bad about change; it just is.
In 43, Marcus returns to the universal theme. Creation, time - they flow like a river. No need to lament; rather embrace.
In 44, Marcus continues the flow of time and change theme. Embrace the change; love it.
In 45, Marcus love the fate and the change of the universe. It is all connected and rational.
(see also Citadel p. 66, 116-117, 141, 253)