I am studying this book now and it is one of the most informative I have read in quite a while, and I read a lot of books.
Scott Iardella shows numerous reasons why strength is so important all through life, but especially as you age. He covers some subjects in depth that many people may not have looked into before, like muscle wasting (sarcopenia).
The Edge of Strength: An Unconventional Guide To Live Your Strength And Discover Your Greatness
The Cave 