The Dip: A Little Book that Teaches You When to Quit (and When to Stick) by Seth Godin.
Godin is a marketing guru & prolific blogger. This book is about 78 pages, so it reads more like a long blog post and you can read it in less than an hour.
The "dip" Godin refers to is that point in any activity where the activity becomes difficult and requires serious commitment to complete. Becoming a CPA, or learning to surf, or getting a PhD are some examples of activities with serious dips. You enter into the subject area with zeal & interest and then probably quit when the going gets tough. And this is stupid because if you were mature, you'd have not gotten into the activity to begin with (not bought a surfboard, for example). And if you just hang on and determine to be the best in the world, then you'll be a scarce and valuable commodity. Quitting in the middle of the dip is often stupid, but we do it all the time.
The book is about quitting those tasks at which you're not going to be the best in the world at in order to focus on other areas where you WILL become the best in the world at. That's your goal: Be the very best there is. You should also quit your dead-end job and look for one that you can move upward with.
There's nothing really insightful in this book, just a way to evaluate where you're at in your job, career, etc. But Godin assumes that career is the most important thing. He counsels one person to quit because that person has achieved stability at his current job. The fact that the guy now can spend more time with his family after seriously making them sacrifice for him for years doesn't factor into Godin's advice. In fact, Godin basically says "Yuck, apple pie is mediocrity. Quit your job and take risks again." The guy probably could have kept his good job and instead worked on stepping up his game as far as his commitment to wife, children, community, etc. I'm reminded of many of Nassim Taleb's almost daily tweet snipes about business writing.
I give it about 2.5 stars out of 5. If you have an hour to kill in a Barnes & Noble somewhere, then check it out.