It seems to be a philosophy about being a good little productive serf and continuing to be productive while taking your powerlessness on the nose? Why would anybody in a modern free society follow this philosophy?
As to why someone would follow the philosophy, it's simple: we all face stressful situations in life (some more stressful than others of course). Why should you let those things rule your emotions? It doesn't help anything to get upset. It just makes you feel worse. It is a pure negative thing in your life. So, you work to try to gain mastery over those feelings so that even when life is hard you can face it more effectively and with greater peace of mind.