This expression is oftentimes used to describe the unhealthy circumstance of a person who has so much work to do (or chooses to work so much) that they do not have time for personal matters in life.
只工作不玩耍，聰明的孩子也變傻。
時時刻刻，日復一日，唯有勤奮用功，而絲毫沒有娛樂或調劑，任誰都會受不了的，不單是 Jack (傑克) ---- Jack是常用英文名字，拿來做代表罷了