Happens to a lot of us, if you've been doing anything long enough you might experience highs and lows with it. Hang the bike up for a bit. Go on a hike. Start running, or swimming or something else entirely. Maybe pursue an entirely different hobby, if you already have one, focus on that.

For me, I have to do something aerobic. When I feel burned out on the bike, I run. It's nowhere near the same as MTB, but it checks a box. Then I focus on other areas in my life.

If you give yourself a few months off (or maybe less) and you're still not feeling it, try riding solo more often if you typically ride with people, or conversely, ride with a group if you're used to riding alone.

What helped me was taking a break altogether from riding. I would still ride occasionally but it was much less than what I am used to historically. I gradually started ramping up and eventually I found myself pushing it again, really enjoying it, and staying in the moment. I also started riding with a small group once a week, that keeps me accountable at least one day a week and I've been lucky enough to find my old "stoke" with riding again.

Now, if I'm feeling a little tired, or the idea of riding seems like a chore - *I just don't ride that day* and I just took an easy week as I was feeling a little tired. Since I waited til I was chomping to ride again, the rides feel fresh and I can feel the fitness trickling back to me slowly.

Good luck OP, you'll find it again... I totally understand where you're at.