I find this advice challenging to accept.
According to him follow your passion is the wrong advice. He has examples to substantiate and back up his claim of why not to follow your passion.
However, What struck me most is the concept of Building "Career Capital."
The focus on stretching your ability and receiving immediate feedback provides the core to successfully acquiring career capital in almost any field. Deliberate practice invested in honing your skills might give the key to quickly becoming so good they can't ignore you.
In short, it is not just having a passion for something that helps one becoming successful, but one has to invest in practising the skills to make it perfect—some valuable insights on how to build your career.
I would recommend this book to anyone looking to build a career that gives you more autonomy, a sense of fulfilment, and control.