Fasting correctly

"Do you fast? Then feed the hungry, give drink to the thirsty, visit the sick, do not forget the imprisoned, have pity on the tortured, comfort those who grieve and who weep, be merciful, humble, kind, calm, patient, sympathetic, forgiving, reverent, truthful and pious, so that God might accept your fasting and might plentifully grant you the fruits of repentance. Fasting of the body is food for the soul."
—St. Basil the Great, 329-379 A.D.

"Prayer, fasting, vigils, and all other Christian practices, however good they are in themselves, do not constitute the goal of our Christian life, although they serve as a necessary means to its attainment. The true goal of our Christian life consists in the acquisition of the Holy Spirit of God. Fasting, vigils, prayers, alms-giving and all good deeds done for the sake of Christ are but means for the acquisition of the Holy Spirit of God. But note, my son, that only a good deed done for the sake of Christ brings us the fruits of the Holy Spirit. All that is done, if it is not for Christ's sake, although it may be good, brings us no reward in the life to come, nor does it give us God's grace in the present life."
—St. Seraphim of Sarov (a famous and highly revered Russian Orthodox saint, 1754-1833 A.D.)