I just got 'Never Gymless'. LOTS of great workout ideas in there, as well as general information about types of strength, types of exercises, and general conditioning. It is written in a very informal, readable style, but still covers the subject with some good depth.
As a 47-yr-old middle-aged Mom, I am definitely not in danger of being mistaken for 'She-Hulk the Barbarian MA Warrior'. The exercises/workout routines in the book cover the whole range, so they would be appropriate for a serious fighter-in-training. At the same time, the book gives some great ideas on how to build up to the more complex/difficult exercises, so someone like me (who can barely do one body-weight chinup) can also benefit.
The premise of the book is NOT that body-weight exercises are the be-all-to-end-all, but that you can develop a credible workout and build or maintain your fitness level, even if you have no access to a gym membership or expensive equipment. For those of you building your own 'home gym' with makeshift or borrowed equipment, for students on a budget, or for those who have time to train but not time to make another trip out to a gym/fitness center/weight room, this book is for you.