Ash Wednesday and Good Friday are days of Fast and Abstinence. All other Fridays of Lent are days of Abstinence.
Fasting is to be observed by all persons 18 years of age and older who have not yet celebrated their 59th birthday. On a fast day one full meal is allowed. Two other meals, sufficient to maintain strength, may be taken according to each one's needs, but together they should not equal another full meal. Eating between meals is NOT permitted, but liquids, including milk and juices, are allowed.
Abstinence is to be observed by all persons 14 years of age and older. On
days of abstinence no meat is allowed.
Note that when health or ability to work would be seriously affected, the law does not oblige. When in doubt concerning fast and abstinence, the parish priest should be consulted.
Week Days of Lent:
There is no obligation to fast during the week days of Lent (other than on Ash Wednesday and Good Friday), however, voluntary acts of self-denial are recommended. Fasting, almsgiving, and prayer are three traditional disciplines of Lent. The faithful and catechumens should undertake these practices seriously in a spirit of penance and preparation for baptism or the renewal of baptismal promises at Easter.
Easter Duty Obligation:
Must be made from the first Sunday of Lent though Trinity Sunday.
Voluntary Self Denial: In addition to fasting, these may include: participation in daily Mass, Spiritual studies, Lenten Devotions, Stations of the Cross, saying the Rosary, deeds of mercy and kindness.
Vigils and Ember Days: While there is no longer an obligation for fast or abstinence on "vigil days", Catholics are expected to practice self denial on a voluntary basis. Vigils have been traditionally marked as a day of penance before a Feast such as Christmas and Easter, while Ember Days came four times a year and date from the fifth century, probably as Christian replacements for seasonal festivals of agrarian cults.
Teach us, good Lord, to serve Thee as Thou deservest:
To give and not to count the cost;
To fight and not heed the wounds;
To toil and not to seek for rest;
To labor and not ask for a reward
Save that of knowing that we do Thy will.