Is one that actually delivers value in return for your time and energy reading it. Seneca's On the Shortness of Life is that kind of book. I won't add anything, I just want to share some of my favorite passages. The book is just over 100 pages and is ridiculously easy to digest. You can finish it in one sitting, but I would recommend getting this book and coming back to it from time to time. Each time you'll get something new.
He opens on a light note:
One of my favorites:
A slap in the face to most people working 9-5 or 9-6 0r 9-7....you get the point:
And one more. If you made it this far, good for you - go get the book. You'll be happy you own it: