In the context of today.s moral and ecological crisis, and the accelerated advance of information and communication technologies, when human beings intensively experience their own fragility, a major question is that of well-being. That raises the issue of moral health, which represents, in an axiological and normative sense, a basis for the human being to find proper opportunities for remaking and protecting the beingness’ equilibrium in face of a variety of risks in a society of excesses. We consider that a significant element of moral health lies in the old Greek value of sophrosýne. In this essay, we highlight its meaning and role. We do this by reviving the core of a wise learning coming from Ancient philosophy about one of the moral excellences. Sophrosýne is approached as a necessary factor in human well-being; it is pursued in the prophylactic and therapeutic potential for the maintenance of human health; finally, it is developed in its fundamental action of allowing happiness in a well-functioning and self-fulfilling life of the human being.