Luther might say, in “faith working through love,” since it is love that allows a person to “gladly give his endeavors to his earthly tasks, filling his neighbor’s needs and attending to his vocation” according to Gustaf Wingren in Luther on Vocation.
To Luther, love is a natural expression of faith. “A person’s health shows itself in all his doings; it consists of outreaching functions, even though he who acts does not consciously ascribe his actions to his health. But when he falls ill, he notices that he is unable to do the things he formerly did. In like manner love ceases when faith ceases,” and “his vocation weighs upon him with its demands,” becoming “a cross, not a joy.”
In other words, faith transforms how a Christian works. “Law, as it is embodied in the many offices, had the function…to compel man to serve others, whether or not he wished to do so.” In this way, “vocation operates with coercion, without his heart.” But, “in faith,” the heart has been made new.” “Our neighbor with his need does not press upon us against our will; rather he fills us with gladness, for it is our joy to serve him. What earthly government would compel we now do freely.”
Love, a natural expression of faith, “overcomes all circumstances,” and “gladly does what vocation calls for.”
One implication: if I find myself unable to approach work with love for those I serve through it, and my job becomes a burden, then I am lacking in faith.