What are the four Orthodox fasting seasons, and why is one harder than another?

So we have four main fasts of the year. I actually think of this, right, wrong, or indifferent, I think of this like a training schedule for weightlifting. The church calendar begins with the Dormition fast, which is a very serious and strict and solemn fast that comes before the Dormition of the Mother of God. It kind of kicks us off with a bang, but it's very short. It's only two weeks. And then we get into a more relaxed fast with the Nativity fast. All the fish days signify are the rank of the saint and the strictness of the fast. So when a great saint is celebrated during Great Lent, we don't eat fish. But when a great saint is during Nativity, then we eat fish. So the Nativity fast is long, forty days, but it isn't, how could you put it, maybe super challenging. It has lots of fish days. You eat fish on the weekend. Almost every single week has one or two days that are commemorating a saint that has a fish on it. That's really all it is. It's a more relaxed fasting day to commemorate somebody who has great significance within the church. We obviously end the forty days with the birth of Christ. And then within usually a couple months, two to three months, we kick off the Lenten fast. Now, the Lenten fast is the fast of fasts. It's the strictest, most serious fasting time of the year. So if you think about it in terms of weightlifting, you have like a block periodization where you go hard, then you take a rest, then you go a little harder, then you take a rest, and then for Lent it's like you go as hard as you can. And it's forty days, and then there's Holy Week on top of it. So we don't count Holy Week, but it's another six days of fasting. Also, the character of Great Lent is one that is very solemn. Somebody, I once read in the life of a saint, said something along the lines of, people would even try to refrain from laughter during Great Lent. Now that may be kind of foreign to us. That's okay, we're not eighteenth century villagers. But the idea behind Great and Holy Lent is it is our Olympic training cycle, right? So people often forget with athletes, they work hard all year to maintain a certain level, and then they push themselves extremely hard right before the Olympics, and then they have the Olympics where they're basically super exhausted, beat up, but pushing their body to the absolute red line. That's kind of how Great Lent is.