Don't think I'll be buying the book. In any given week I have about about four stretches of continuous motion, either running or walking, last between 50 and 90

Don't think I'll be buying the book. In any given week I have about about four stretches of continuous motion, either running or walking, last between 50 and 90 minutes. It is very seldom that I get the "can run forever" feeling that I sometimes got as younger, leaner, fitter man.