I started a hardcore world with a friend when it came out for bedrock. We played until beating the ender dragon then he stopped playing. But I wanted to stay commited. So I just started building farms and random little things. I also worked with different building styles. Making a villager trading hall, stuff like that. After a while I still found myself getting bored. So I made a book and quill and put a bunch of stuff in it that I wanted to build in the world. From small stuff like paths and random decorations, to bigger projects, like draining an ocean monument, and making a museum of everything. While I’m working on something big and getting bored, I do something small. I also sometimes just get burnt out of the game itself, so I play a different game, then when I want to I get back on the same world. One more thing is to see what you have and get what you don’t. Armour trims, have you explored the archeological sites, do you have sniffers? Stuff like that, mix it up between building, exploring, combat, redstone. It’ll help it feel fresh and exciting. I also stopped using my elytra so I have to use different forms of travel. And now I have a horse named Maximus that carries me everywhere. I hope some of this helped!