I forget how I came across Forever Employable--I think I heard about it on a podcast at some point--but I bought it about a year ago and got around to reading it this past week. It's short, only 106 pages, and it's a very quick and easy read. The book is basically a how-to guide to creating a niche for yourself in whatever industry you believe can become an expert. The ultimate objective in this journey is to become a wanted entity in your area of expertise, and thus shift from a beggar's situation (my words) to that of a self-perpetuating income generator (again, my words). In the book, Gothelf recounts his own crisis/awareness in his mid-30s about his career potential moving past 40.
The book is simple, has some good insights, and is a fun read. It's not groundbreaking from any vantage point and may be overly-driven by some of the privileged assumptions of the tech world (not everyone has the background, education, experience, etc. to build what he describes), yet in his attempt to elucidate the process he went through, he does indeed offer some good insights and a simple, practical framework to chunk through his defined steps and see if you can build some results. The biggest missing piece is that he does not dive into the underlying tools to build discipline, persistence, or consistency -- he seems to assume that the fear of pending irrelevancy in your 40s should be enough fuel to drive the discipline.
This is a good book for someone looking for a kind of simple guidebook to shifting out of an 'employee' mentality and into a more entrepreneurial, independent mentality and generating some non-traditional income streams over time. Despite my notes above, I did like it and it brought some ideas into focus in a very clear, reproducible way.