It is not ideal to under-save money, leaving you unprepared for emergencies. It is certainly unpredictable what is enough for an emergency, therefore, we resort to keep earning more. Besides, our culture applauds the virtue.
But it is an inefficient use of our life energy to over-save money. Excess money upon our demise means we devote too much time to make more money than we can spend.
Recognizing the ebbs and flows of our health and wealth which tend to move inversely to one another over time, it is wise to spread out our allocation of pursuit of work and play.