What was the old style of penance, before modern indulgences?

In [this answer](https://christianity.stackexchange.com/a/19372/31636) , it is mentioned that the times listed for various indulgences > corresponds *not* to that amount of time off Purgatory, *but* to a remission equivalent to what one would get from performing "old-school" penance for that duration. The poster quoted a specific example of such an indulgence: > An indulgence of three hundred days is granted to all the Faithful who read the Holy Gospels at least a quarter of an hour.... 13 December, 1898. LEO XIII. Doing the math, this results in the ratio of the effectiveness of this Bible reading indulgence over "old-school" penance being 28,800:1, a truly staggering gain. This makes me wonder what was really involved in old-style penance, which apparently was cosmically super-ineffective compared to 19th century indulgences. What was actually involved in this "old-school" or old-style penance? To be clear, I'm not asking for an analysis of penance or indulgence calculations or equivalencies, but in what a person doing "old-school" penance actually did. What a person does to obtain a modern Indulgence is pretty well defined - say this prayer 10 times, read the Bible for 15 minutes, wear this medallion for a month, pray at least 30 minutes at this shrine on Christmas, etc. Ken Graham's mention of "Some indulgences in the 'old days' carried the phrase as being equivalent of doing a 40 day fast of quarantine." is hinting at what I am asking. What would be involved in *doing* a fast of quarantine? I know you have to *fast*, but how strict is that and what specific rules must be followed (e.g. things one is permitted to do, things one is forbidden from doing, serious violations that invalidate the penance or reset it back to zero days)? Suppose (hypothetically) I went back in time to the days of "old-school" penance and went to confess to a priest, who advised me to do 40 days of penance. Being an ignorant 21st century time traveler, I ask him, "I've never done that, what is it I actually *do*?". Would any of the following be remotely close to what he would say? - Do I have to put on a sackcloth robe and go live in the woods for 40 days, surviving on leaves and mushrooms? - Do I get assigned a set of prayers to say or Bible verses to read for each of the 40 days, but otherwise go about my life normally? - Do I have to do self-flagellation each day for 40 days? - Do I go live at a designated Penance Center, which is kind of like a modern Retreat Center, but, y'know, harsher? - Do I just mope around feeling sorry for myself for 40 days and make sure to drink fewer than two alcoholic beverages a day, except on Tuesdays, when I can have three as long as I avoid red meat for the rest of the week? - Something completely different? Whether or not "old-school" penance is still done in modern Catholicism (e.g. can be assigned by a priest, has some sort of spiritual effect, etc.) is a completely separate question that someone could ask, but it's not this question.