Having read the book I have this comment to make. I have been walking and running all my life, as a firefighter I was extremely fit. However after an accident I hurt my back and was unable to run ever again. This didn't stop me walking and I walk every day. So I agree with the benefits of walking with the exception of I now have Type II diabetes heart problems and cataracts, I am at least a stone overweight and have not found a way to lose weight . Most of these problems are caused by my medication to help with my heart problem.I get out of breath walking up the slightest slope but none of this stops me walking. So read the book and enjoy it what don't expect it to solve your health problems as you get older because it won't. Walking is probably the best thing you can do as a form of exercise even if it kills you.