“Remember that you are an actor in a play,
which the playwright wills;
if short, short; if long, long;
he may intend you to play a beggar
so that also you might act this naturally;
or a cripple, an official, or a private person.
For this is yours, to play the given role beautifully;
but the selection of it is another’s.”

Epictetus

To answer, “what is in my control?” is a very important aspect to gaining tranquility.  I didn’t plan on having to replace my sideview mirror, but it looks like I have to now.  Yes, I erred and struck one of those big orange barrels (why to they have to make them so rigid and heavy).  I thought that the one before it was the last one, so I started to enter the lane to my right.  Not so fast!  There’s another barrier, and…BAM!  I have gone from everyday driver to guy who needs a new mirror.  I didn’t plan for this to happen, but it has changed my role.  Was it in my control to not hit that large cone?  Well, to some extent.  There were outlying factors:  I was tired, it was dark, I was sucked in by an optical illusion, and possibly the barriers were placed too far apart….but we all make mistakes.  So this outcome was partially in my control, and I misjudged.  Now, my reaction to it is COMPLETELY in my control.  This reaction is governed by how well I play my new role as “flawed driver, who must now remedy his broken mirror.”  Don’t get me wrong, I was peeved, mostly at myself, but my Zen/Stoic outlook helped me refocus back to a state where I could deal with my new lot in life.

It could have been worse!

A Stoic must be able to pick up new roles as things happen to him.  For example, you may be a welder, but then you are fired.  Your new role is to find new work.  That is your role, now.  I can wallow in self-pity or I can take on this role with “passionate equanimity.”  The equanimity helps you understand that there is nothing you can do about how you’ve been fired.  The passion allows you to do your best to find new work.