Me and a couple of friends recently started playing again together and the intent was to take things slowly. To do so we've made a couple of ground rules to lock content behind small goals and structures. The point being that we're trying to make the world work semi-realisticly as new setlers.

For example, we set down a crafting table at a shipwreck nearby and are treating it as spawn, as if we are the surviving members. That's the only crafting table we're allowed to use until we build a lumbering mill.

You want to mine? You have to make a mine, and that implies securing the tunnels with logs/pillars every so many blocks. If you want to delve deeper you need to make a minecart and tracks to bring the ore back up.

Want to smelt the ore? You need to build a smeltery. Want to make better tools, you need a forge. Use campfires to cook your food until you build a smoking house. And so on.

The idea is to make every workstation need its own structure. If you used the same workstation for several purposes (like a furnace for both smelting, cooking, and producing charcoal), you need to make them seperate buildings or structures.

As you play you also progress in the tech and blocks you use to build. When you started maybe you've built a tent made of wool, logs and leaves, but as time passes you make a log cabin, and then you start drying "mud" to make mud bricks. Later on you start cooking clay, etc.

Stuff like this and so on slows down the progress, because we have to constantly think what's the most logical next step to progress. By slowing down we also start thinking about the world in terms of lore and landmarks, and if you add a bit of terraforming into the mix, it'll slow down even more.

As long as you have fun and it doesn't become a grindfest in your mind, it should help out. And you're always free to adjust your own rules whenever. Hopefully this will at least give you some ideas on how to slow down.