Richard Foster said this quote

A Spiritual Discipline is an intentionally directed action which places us in a position to receive from God the power to do what we cannot accomplish on our own....The deep waters of God's life are already flowing. We simply learn the strokes that will enable us more and more to be at home in them....The human body is our power-pack of mind-body-spirit -- we discipline it in order to practice cooperation with God. (Life with God, p. 135-137)