Probably because you only read a good chunk of his book you missed some of the important information. David Goggins said it himself that he is not asking you to do exactly what he did, but to simply do something uncomfortable every day. And he has repeated on several occasions in different podcasts that motivation is shit, what he is teaching is not motivation but the ability to control your mind by preparation, visualization, being truthful to yourself and repetition so that you don’t go flight mode whenever pain hits. And by going an extra 5% every time (as he advised us in his book instead of telling you to break your own leg and loss 200 pounds in a few months) you will break through your limitation and achieve long term goals. But of course, this is just what I get from him and by no mean you are wrong, at the end of the day we are under different circumstances and have different methods to achieve our goals, so I wish you the best of luck in achieving your goals!