This gift helps the soul bears suffering with equanimity, that is with an even soul. This gift affects ones initial reaction to evil inflicted on us. When something evil is done to us we can react with anger or bear it with mildness. This fruit of mildness giving us evenness of mind whereby we are neither elated nor depressed. This fruit helps us to curb anger, that knee jerk reaction to annoying things. This fruit is essential for carrying out the virtues of gentleness, temperance, and charity.
Having borne that initial instance of evil we still may need to wait a while till the evil has passed. This is where the fruit of long-suffering helps us. This gift helps us patiently suffer evil over a long period, most especially from those with whom we dwell. Kindness will help us to cure the these evils and goodness to forgive the evil, but long-suffering is that boost to do the distance so to speak.
So whenever you see some good thing delayed and beyond your reach ask ardently for an increase of this fruit from the Holy Ghost.