job burnout(Merriam-Webster's Collegiate Dictionary "exhaustion of physical or emotional strength or motivation usually as a result of prolonged stress or frustration" West_LV)
work to the point of burnout(The ideal that motivates us to work to the point of burnout is the promise that if you work hard, you will live a good life: not just a life of material comfort, but a life of social dignity, moral character and purpose in life.theguardian.comAlex_Odeychuk)
