An often-overlooked benefit of praying is the gaining of indulgences, which the Church attaches to many prayers that can remit temporal punishment associated with one's past sins.
As Bd. Pope Paul VI explained in 1967 in his apostolic constitution Indulgentiarum Doctrina:
An indulgence is the remission before God of the temporal punishment due sins already forgiven as far as their guilt is concerned, which the follower of Christ with the proper dispositions and under certain determined conditions acquires through the intervention of the Church, which as minister of the Redemption, authoritatively dispenses and applies the treasury of the satisfaction won by Christ and the saints.
This concept wasn't made up by the Catholic Church but was inherited from Judaism as recorded in the second book of Maccabees — a book included in the Greek Septuagint, part of the Old Testament at the time of Christ. The following incident in 2 Maccabees 12:42–45 was a record of what Judas Maccabees and other zealous Jews believed and practiced in their day regarding fallen soldiers:
And so betaking themselves to prayers, they besought him that the sin which had been committed might be forgotten. ... And making a gathering, he sent 12,000 drachms of silver to Jerusalem for sacrifice to be offered for the sins of the dead ... and because he considered that they who had fallen asleep with godliness had great grace laid up for them. It is therefore a holy and wholesome thought to pray for the dead, that they may be loosed from sins.
Join Church Militant in prayer every morning and evening at 8 a.m. ET and 4:45 p.m. ET as we pray with Holy Mother Church and gain many indulgences for you or for the poor souls in Purgatory.
Watch the panel discuss the value of daily prayer in The Download—Praying With the Church.