It is the part of a Christian to take care of his own body for the very purpose that by its soundness and well being he may be enabled to labour... for the aid of those who are in want, that thus the stronger member may serve the weaker member, and we may be children of God, and busy for one another, bearing one another's burdens, and so fulfiling the law of Christ.

First Principles of the Reformation, Or, The Ninety-five Theses and the Three Primary Works of Martin Luther (ed. 1883)