Look at Dr. Jeffrey S. Life. He's a 72 year old doctor who won the “Body for Life” program for his age group and how has written a book about what he is doing to defy the “You lose muscle as you age.” I went to his website, and he seems legit. He seems very open (as he talks about using growth hormones – if tests show you need it – so its somewhat controversial) and has already answered the question “Is that picture photoshopped?” about a million times (its not). He stated in an interview on his website, that you can achieve results without roiding up (OK, I'm paraphrasing).
The point is by taking positive steps, and doing the right actions, and eating the right things do not stop working as you get older. The hard cover is $16, and the Kindle is $13. I've already sent the “preview” to my Kindle (one of the things I love about the Kindle).
The one thing that makes me hesitant about Dr. Life is his website has him on a “Show” called the Wellness Hour. If you watch to the end you see where “The Wellness Hour” is a paid program (better known as an infomercial – no wonder the host was so impressed and seemed to ask the right questions).
If nothing else, this guy is inspirational, if anyone has read this book please let me know.