So, I’ve heard that during Lent it’s okay to eat/do whatever you gave up on Sundays because we’re supposed to consider a “Mini Easter”, that’s correct right?
If it is, then can anyone tell me where and when that came from? Thank you very much! 
I remember one year I gave up something difficult for Lent. It was actually my spiritual director who suggested it and I agreed. But I said to him “I can have it on Sundays, right? They aren’t included in the fast days.” He said “This is your sacrifice so you can make up any rules you want. I’ve never bought into the Sunday-exception idea myself.”
I think he was right. It’s your Lent and your sacrifice so you can make up any rules you want to govern it. But I’ve gone with the idea that if I’m doing something for Lent, I’m doing it for all of Lent.
It is true that we do not fast on Sundays, but as far as Lenten sacrifices go, one would have to decide why one is giving up what they’ve chosen.
I would think that in some cases, relaxing the fast on Sundays might make the fast more difficult.
If you are giving up something which is sinful and/or unhealthy, then stopping the fast on Sundays would just not make any sense.
I remember talking to an adult woman and I mentioned that we are not required to continue the Lenten fast on Sundays. She was really upset that I’d told her that!
Oops.
I believe the reasoning behind not doing PENANCE would be that Sundays are Feast/Celebration days… not penitential days; and yes, they are “mini Easters”. So it makes sense that you wouldn’t do the penance on Sunday.
Keep in mind that the norm before 1962? was that you had penance on EVERY day during Lent EXCEPT for Sundays or Feast Days during Lent. I can’t recall off the top of my head if it was fasting AND abstinence, but I want to say that it was. So Sunday was very much a needed break!! And it kept with the spirit of celebration on Sundays too.
Maybe you are looking at it wrong. If it is harder to give something up on the weekdays and then be “off” for a day… maybe that’s a GOOD reason to do it, not a negative reason! 
After all, it IS a season of penance… so if it’s harder, that’s better, right? 
In the early Church, the cycle of Friday-Sunday was considered to be a mini-Lent/Easter season. It became a once-every-year-for-40-days process around the 4th century after Christ. Sunday is always a day of rejoicing and feasting no matter what happens before or after it. Deo gratias.
You can’t give up something sinful for Lent as your Lenten fast. That’s the problem: the western culture is, more and more, treating Lenten observations as a religious form of New Year’s resolutions.
We are called at ALL times of the year to give up on ALL things sinful. So giving it up for Lent is not a special commitment to fasting, it’s merely a part of formative Christian life.
Lenten observations are sacrifices of something we are ALLOWED but do not NEED. The loss is to remind us of Christ’s fasting, abstaining from enjoyable things and reflecting on the suffering of Christ.
No, he was not right.
If you’ll see my above post, you’ll see why the Sunday exception is not BAD: because Lenten sacrifice is to be something we are allowed, enjoy, but do not need.
That’s because a Lenton sacrifice is a forty day fasting. However, no fasting is allowed on official feast days, and all Sundays are feast days (a good general rule: if it’s a holy day of obligation it’s not a fast day).
So you can choose NOT to partake of whatever you gave up, but you should NOT feel obligated to remain in fasting on a Sunday as a result of Lenten commitment, and it is wholly incorrect to observe the Sunday exception as somehow wrong or misguided.
(and no, you can’t make up any rules you want for Lenten observances)
Our dear priest also mentioned today at Mass that it’s important to give up something that you don’t WANT to give up. To give up those things that we treasure on earth for heaven instead. So it would be great to pick the thing that you don’t want to give up and do that. Then you will probably very much welcome the break on Sunday! LOL