When we ask you to fast for 3 days prior to certain feast days, we don't mean you should eat nothing at all for three days. Even the canonically required fasting on Ash Wednesday & Good Friday is not that strict. On those days, the Church requires all Catholics between 18 and 60, under pain of sin, to abstain from meat and to eat no more than 1 full meal and 2 smaller meals. Those 2 smaller meals should be less than a full meal when added together. For example, you could have a small granola bar for breakfast, a full lunch, and a piece of fruit for dinner.
You can think of this fast according to 3 criteria:
1) Genuinely Sacrificial: Pick something that actually feels like a sacrifice. It isn't really a good "fast" to give up drinking alcohol when you don't drink 9 out of 10 days already. Likewise, if you never eat meat, giving up meat on that day isn't very effective. Pick something that you'll feel so that at least a few times throughout the day will make you pause and say "I kinda wish I could have ___ right now. Ah well, I'm doing it for you, Lord."The Paschal Triduum (Holy Thursday, Good Friday, Holy Saturday) is a special situation. For the other days, we've asked for fasting leading up to the feast, but this one has fasting in the midst of it. Obviously you have to fast on Good Friday and that has to be the canonical fast. We'd also ask you to fast on Holy Saturday at least until the end of the Easter Vigil. The question is what day to add to make it 3 days. Because Holy Thursday is itself a celebratory day, it's a bit tricky. There are two ways to approach this. Depending on which kind of fast you pick, one or the other might make more sense to you.
- You could fast on Holy Wednesday and treat all day Thursday as a feast.A great way to make a fast more bearable is to have something to look forward to after. This is why fasts have always been connected to feast days. Now, attending Mass is definitely a celebration in it's own right, but our personal lives should echo that celebration. This is why we encourage you to plan ahead and schedule an actual feast of some kind with family and friends: a nice restaurant, something at one of your homes, a parish event. That way, when day 2 of the fast hits and you're a little weary of it, you can look forward to that event.