Another useful one coming right out of the Stoic tradition is the trisection into things that one
1) has no control over, such as weather, other people's actions, etc.: do not fret about those.
2) has complete control over, such as one's thoughts, judgements, response to events, actions, etc.: concentrate on these.
3) has partial control over, such as one's health, reputation, etc.: do not fret about the outcome, but prepare/do your part as best as you can.
This is well explained in William Irvine's Guide to the Good Life [0], but has already been proposed by Epictetus in the Enchiridion [1], 2nd century CE:
> Work, therefore to be able to say to every harsh appearance, “You are but an appearance, and not absolutely the thing you appear to be.” And then examine it by those rules which you have, and first, and chiefly, by this: whether it concerns the things which are in our own control, or those which are not; and, if it concerns anything not in our control, be prepared to say that it is nothing to you.
1) has no control over, such as weather, other people's actions, etc.: do not fret about those.
2) has complete control over, such as one's thoughts, judgements, response to events, actions, etc.: concentrate on these.
3) has partial control over, such as one's health, reputation, etc.: do not fret about the outcome, but prepare/do your part as best as you can.
This is well explained in William Irvine's Guide to the Good Life [0], but has already been proposed by Epictetus in the Enchiridion [1], 2nd century CE:
> Work, therefore to be able to say to every harsh appearance, “You are but an appearance, and not absolutely the thing you appear to be.” And then examine it by those rules which you have, and first, and chiefly, by this: whether it concerns the things which are in our own control, or those which are not; and, if it concerns anything not in our control, be prepared to say that it is nothing to you.
[0] https://www.goodreads.com/book/show/5617966-a-guide-to-the-g...
[1] https://standardebooks.org/ebooks/epictetus/the-enchiridion/...
(Note that standardebooks is pretty cool, a non-profit offering carefully formatted, open source, and free public domain ebooks!)