I'm in the same boat -- I'm 45 and a mediocre mountain bike racer, but over the last few years my motivation to train has gone down considerably. The problem is bike racing has been my "thing" for so long that's it's weird to think of cycling season coming and going without me.
I raced road bikes throughout my 20s. A few days ago I hit the 10 year anniversary of my last race. At this point in my life, I can barely relate to the person who practically organized their whole life around racing and was deeply embedded in the local scene. But I completely relate to your feelings about the season coming and going. Even a few years after hanging up the cleats, I would still sometimes get the itch to drop into my city's local crit. There is something a little cultish about bike racing that is hard to give up. I don't know anyone who managed to have a healthy relationship with it for more than a decade. But it is a lot of fun at its best.
> I don't know anyone who managed to have a healthy relationship with it for more than a decade.
Absolutely! When the 2020 season was cancelled due to Covid, one of my teammates asked "what are we supposed to do now, ride bikes for fun?" They were joking, but I think the sentiment rings true for a lot of people.
What type of racing are you doing? I am stating the obvious here but there is more than one discipline of MTB and switching could give you a jolt of motivation (if you want that jolt).