In order to quit drinking, it is not enough merely to make a firm resolve. One must possess the psychological strength to continue implementing that resolve. Since Naikan therapy is a comparatively restrictive mode of treatment, it may be conjectured that a fair amount of endurance and psychological strength is cultivated merely by going through the treatment itself. And it would seem that the energy to reform on one's own those things that one has discovered by carefully looking at the self on one's own, without receiving any preachy criticism from others, that energy in fact becomes the strength to remain sober.

Vaillant claims that there are seven key indicators of a person's life at age 50 that are pretty good predictors of where they will be (or if they will be) at age 80: "Whether we live to a vigorous old age lies not so much in our stars or our genes as in ourselves."