by Matthew Plese, February 10, 2022 – from https://onepeterfive.com/forgotten-customs-of-septuagesima/
Brethren: Know you not that they that run in the race, all run indeed, but one receiveth the prize. So run that you may obtain. And every one that striveth for the mastery refraineth himself from all things. And they indeed that they may receive a corruptible crown: but we an incorruptible one. I therefore so run, not as at an uncertainty: I so fight, not as one beating the air. But I chastise my body and bring it into subjection: lest perhaps, when I have preached to others, I myself should become a castaway (1 Cor. 9:24-27 as taken from the Epistle on Septuagesima Sunday).
Septuagesima is the ancient period of time observed for two and a half weeks before the start of Lent. Celebrated on the Third Sunday before the First Sunday in Lent, Septuagesima is both the name of this third Sunday before Lent’s beginning as well as the season itself that runs from this day up until Ash Wednesday. The season of Septuagesima comprises the Sundays of Septuagesima, Sexagesima, and Quinquagesima. The Fourth Council of Orleans in 541 AD documents the existence of this season.
This time, informally called “Pre-Lent,” is a time for us to focus on the need for a Savior. It is a time to prepare a Lenten prayer schedule so that we can determine which extra devotions and Masses we will go to in Lent. It is a time to begin weaning ourselves from food so that we may more easily observe the strictest fast during Lent.