Fasting is the champion of every virtue, the beginning of the struggle, the crown of the abstinent, the beauty of virginity and sanctity, the resplendence of chastity, the commencement of the path of Christianity, the mother of prayer, the well-spring of sobriety and prudence, the teacher of stillness, and the precursor of all good works. Just as the enjoyment of light is coupled with healthy eyes, so desire for prayer accompanies fasting that is practised with discernment.
~St Isaac the Syrian
But let us who are weak and passionate have the courage to offer our infirmity and natural weakness to Christ with unhesitating faith, and confess it to Him; and we shall be certain to obtain His help, even beyond our merit, if only we unceasingly go right down to the depth of humility.
~St John Climacus, The Ladder of Divine Ascent, 1.8