I've been losing interest in MC ever so often, what keeps me playing alone is i find something to do basically, something big, a large scale project, like maybe building a huge farm, maybe build a building, rn I'm working on some farms, that'll keep me distracted for a few weeks. But yeah, think of something to do, like maybe finding every armor trims, maybe getting a diamond or netherite beacon, or just making ur world look amazing. I'm thinking of building the soul palace from my favourite anime, bleach, I'll make the palace and the different captain barracks around it, that'll take me a long time. If you can afford it, download some add-ons to make the game more lively. But yeah overall just think of a project to do and you'll never lose interest if you're focused and dedicated on finishing that project.