There are 2 authors -- one a doctor who goes through the biology (a bit dry) and the older guy (71) who has a very funny and effective voice. So, all in all, a very useful book, but the rating is down a bit by the dry chapters. 'One tidbit -- the "healing" sports: biking, swimming, canoeing, kayaking, cross country skiing. Weight bearing, without negative impact on the joints. Good to know.Harry's rules1. Exercise 6 days a week for the rest of your life.2. Do serious aerobic exercise 4 days a week for the rest of your life.3. Do strength training, with weights, 2 days a week for the rest of your life.4. Spend less than you make.5. Quit eating crap!6. Care7. Connect and commit.