Your Question: Since Sundays aren't part of Lent, does that mean that you don't have to keep to your Lenten sacrifice? Or is that a common myth?

This is a common question, and its answer depends upon how you chose to live out your Lent! Sundays are technically a part of Lent--Lent goes from Ash Wednesday to the Mass of the Lord's supper, Holy Thursday. It is true that if you count the number of days in Lent, there are more than 40--and by not counting Sundays, it gets us closer to 40. Nevertheless, they are still part of Lent (the number "40" a figurative reminder of Christ's desert sojournings, the 40 years the Hebrews spent in the desert, etc.). The reason behind the practice of not observing one's Lenten sacrifices on Sundays, however, is that one is putting more emphasis on celebrating the "mini-Easter" on Sunday. We can indeed "not keep" our Lenten sacrifice that day as we celebrate the Resurrection, which many people do. After all, He is indeed still risen! Whether or not one decides to keep one's Lenten sacrifice that day is a personal choice. Personal sacrifices during Lent are of one's own choosing, unlike the required fasting and abstinence from eating meat at certain times. The point of voluntarily giving up something during Lent is not to follow some kind of law, but to come closer to Christ, and unite oneself more closely to His heart. If you want to suspend your sacrifice on Sundays to celebrate the Resurrection, go ahead! If you think you should keep it to remain in Lent, then by all means do so. Either way, have a faith-filled Lent. May we all journey closer to Christ in union with one another.