At 43, I'm really starting to feel that my body's not doing what I need it to do, which isn't really from lack of sleep or illness, simply...hmm, not sure. This book was pretty blunt and helpful in making me see that there are several, free simple changes that I can and need to make, soon. Ones that my brain had been shying away from admitting.
There are several simple series of questions that if you think about and answer honestly, and then tot up the scores, leads you to simple solutions. Sections 2, 3 & 8 were possibly the best bits for me: The Real Reason You're So Tired. How To Eat and How To Start Exercising When You Don't Really Want To. You will find that not every bit will apply to you, but this is easy enough to follow selectively.
It's just common sense stuff being reinforced, not rocket science, done in a simple, blunt, non-patronising way, and from a neutral perspective, helping the reader to avoid letting excuses and obstacles get in the way.
A good tool, but one that I personally would find more useful in the printed book format, so that I could just read the glossary and go straight to the bits I need. And I'd leave it lying around so that I couldn't pretend I'd never read it and couldn't therefore get away with ingrained bad habits!