The Primal Blue Print's author Mark Sisson was a former world class Marathon runner. In short, after suffering from the effects from the unbalanced fitness provided by high mileage training along with little or nothing else, he began to seek a more balanced approach to fitness and health. The result was this book.
He has come up with an approach to a healthy living lifestyle that is relatively simple and effective. What I like the most about his approach is that he used our evolutionary history to develop his system. By understanding how we evolved to live, it is much easier to understand what we need to do to optimize health and fitness.
This evolutionary approach to health and fitness has been wildly successful, and is a growing movement among health and fitness advocates, and the medical community as well. However, we do not completely understand our evolutionary history, and because of this, there are gaps in our knowledge that allow for different interpretations of the same data. In my opinion, Mark Sisson has made perfectly reasonable interpretation of the available data.
Mark Sisson's approach can be boiled down 10 Principles, all of which have a sound basis in our evolutionary past.
1. Eat lots of plants and animals (natural meats and vegetables similar to the Paleo Diet)
2. Avoid Poisonous Things
3. Move Frequently at a Slow Pace (like walking)
4. Lift Heavy Things
5. Sprint Occasionally
6. Get Adequate Sleep
8. Get Adequate Sunlight
9. Avoid Stupid Mistakes
10. Use Your Brain.
If you are an endurance athlete, you may not like what he has to say about endurance training. Basically he's against it. I think he probably goes a bit too far with his take on endurance training, but I'm quite convinced that too many people equate high volume with high fitness, and they end up as very one dimensional athletes who are not as fit as they would like to believe.
I highly recommend this book. Even if you don't agree with the author's take on endurance exercise, the other aspects of his approach are certainly very sound and worth implementing. If nothing else, this book will give you a lot to think about, particularly if you have never considered health and fitness from an evolutionary point of view before.