If you want something short, check out the enchiridion. Enchiridion means 'manual', apparently, and is really short/concise though profound and not grasped easily on just a first read

The translation I used to use is somewhat archaic so I recently asked here for the best translation of it: https://www.reddit.com/r/Stoicism/comments/nexdez/best_trans...

I'd take your pick out of these 4: https://enchiridion.tasuki.org/display:Code:ec,twh,pem,sw/se...