The rich etymology of “discipline” suggests a conscious divestment of all encumbrances, and then a determined investment of all one’s energies. Just as ancient athletes discarded everything and competed gumnos (naked), so must the disciplined Christian man divest himself of every association, habit, and tendency which impedes godliness. Then, with this lean spiritual nakedness accomplished, he must invest all his energy and sweat in the pursuit of godliness.
Kent Hughes