Days of Fast: Ash Wednesday, Good Friday, The “Easter Fast” (Holy Thursday until Easter Vigil/Holy Saturday) is an ancient tradition that should be observed and encouraged. (One full meal, applies to those 18-59 years of age.)
Days of Abstinence: Ash Wednesday, and ALL Fridays in Lent.
Fridays of Lent: (No meat, applies to 14 + years of age.) While failure to observe penitential days in itself may not be considered serious, the failure to observe any penitential days at all, or substantial number of them without a good cause would be considered a grave matter. Those unable to abstain on any given Friday of Lent are asked to perform some other penitential act or abstain on another day.