Episode 909: Not so fast

And when Jesus saw the multitude running together, he threatened the unclean spirit, saying to him: Deaf and dumb spirit, I command thee, go out of him; and enter not any more into him. And crying out, and greatly tearing him, he went out of him, and he became as dead, so that many said: He is dead. But Jesus taking him by the hand, lifted him up; and he arose. And when he was come into the house, his disciples secretly asked him: Why could not we cast him out? And he said to them: This kind can go out by nothing, but by prayer and fasting. Mark 9: 24-28

“Unless you do penance, you
shall likewise perish.” (Luke 13:5)

The law of abstinence: this refers to abstaining from meat.

The law of fasting: this refers to the quantity of food taken,
also refraining from eating between meals.

Fasting and complete abstinence were obligatory on the following days:
Ash Wednesday
Fridays and Saturdays in Lent
Good Friday
Holy Saturday (until midnight 1)
Ember Days (Wednesday, Friday and Saturday)
Vigil of Pentecost
Vigil of Christmas

Holy Days of Obligation are:
All Sundays
Octave Day of the Nativity (January 1)
Ascension Day
Assumption of the Blessed Virgin Mary (August 15)
Feast of All Saints (November 1)
Immaculate Conception (December 8)
Christmas Day (December 25)