A Lenten sacrifice is a spiritual practice where Christians, particularly Catholics, Lutherans, Anglicans, Methodists, Moravians and the United Protestants voluntarily renounce a pleasure or luxury during the observance of Lent, which begins on Ash Wednesday.[3][4] The tradition of Lent has its roots in Jesus Christ praying and fasting for forty days in the desert according to the gospels of Matthew, Mark and Luke.[5] When Lent is over and Easter Sunday arrives, the faithful are able to indulge in what they sacrificed during the Lenten season.[6][7][8]
In Lent, many Christians commit to fasting, as well as giving up certain luxuries in imitation of Jesus Christ's sacrifice during his journey into the desert for 40 days; this is known as one's Lenten sacrifice.
To fast 40 days without being hungry, was certainly far above the strength of man, but to be hungry at any time is inconsistent with God; for which reason our blessed Saviour, that he might not manifestly declare his divinity, was afterwards hungry. S. Hil. -- On this example, as well as that of Moses and Elias, who also fasted 40 days, the fast of Lent was instituted by the apostles, and is of necessity to be observed according to the general consent of the ancient Fathers. S. Jerom (ep. liv. ad Marcel.) says, we fast 40 days, or make one Lent in a year, according to the tradition of the apostles.
I knew part of the answer involved a tradition where everybody had to "give up" something from Ash Wednesday until Easter Sunday.
Ash Wednesday marks the beginning of Lent - the festival where people give up a guilty pleasure for 40 days until Easter Sunday. Lent marks the 40 days Jesus spent fasting in the desert.
Giving something up is a practice to purify us and prepare us for the celebration of Easter Sunday, so it's a way for us to connect and understand more about Christ and God.