This morning's reading from the Liturgy of the Hours featured this from St. Peter Chrysologus:
There are three things, my brethren, by which faith stands firm, devotion remains constant, and virtue endures. They are prayer, fasting and mercy. Prayer knocks at the door, fasting obtains, mercy receives. Prayer, mercy and fasting: these three are one, and they give life to each other.
Fasting is the soul of prayer, mercy is the lifeblood of fasting. Let no one try to separate them; they cannot be separated. If you have only one of them or not all together, you have nothing. So if you pray, fast; if you fast, show mercy; if you want your petition to be heard, hear the petition of others. If you do not close your ear to others you open God’s ear to yourself.
Fasting is the SOUL of prayer, so says the saint. So if I'm praying for you, I should do so with soul and with fasting.
Catholicism. It's not for wussies.