RE: On the art of quitting and the philosophy of Tommy Angelo.
As stated in the article, quitting is an art. Nothing to be ashamed of, nor feared. If used prudently, it can also teach us a lot about ourselves. Our limits, our boundaries and more.
That doesn't mean we have to accept those limitations. It simply means they exist within us at that moment in time. We can then strive to overcome them. Perhaps its a physical limitation that more exercise/workouts will overcome, perhaps its a mental fear/block that we need to look within to overcome.
By knowing when to quit it does not mean you are giving up, simply that you have recognized you are not at a stage where you can conquer or master that particular moment in life.
As @professorbromide mentioned the idea that has been beaten into society for eons (mostly into us males) comes from participation in sports or other "external" activities. While these moments certainly do have value and importance, some fans/players are quite rabid, they in general do not have long lasting, life impacting implications. They are for entertainment when distilled down to the base element.
Therefore, quitting is seen as quite distasteful, an anathema in fact. It denotes poor sportsmanship (another topic altogher), laziness, lack of team spirit/support. All the traits you are supposed to learn to go on and be a productive member of society.
However, like most things that are taught to us as children, the effect or impact becomes magnified exponentially as we grow up. What we once did for fun, becomes a hobby, then a job, then a multi-million dollar career and suddenly the idea of quitting is one as Vince L. describes.
What does that say about us as a society? We need more coaches/books/teachers such as Tommy Angelo who realize that quitting does not equal giving up and sometimes the strongest thing an individual can do is recognize their failures and work to overcome the, bettering and improving themselves, rather than banging their head against a moment they will never succeed in. Thing long term, not short.