So what am I supposed to give up on Fridays during Lent? I normally follow a fish/vegetarian diet all year long, so there’s no sacrifice in giving up meat on Fridays during Lent.
Strictly speaking, you are already doing your duty by giving up meat on the Fridays of Lent and need not worry. However, should you desire to do more as a voluntary personal penance, I have heard of some lacto-ovo (i.e., milk-egg) vegetarians choosing to take up a vegan diet during Lent. You might post this question in the Spirituality forum to solicit ideas for Lenten dietary sacrifices from other Catholic vegetarians.