Sourdough donuts
Used the recipe on Perfect Loaf, way too long to detail here but the ingredients are, for 18 of them (he always has these weird odd measurements like 101, I do often round them with no ill effect but will write them as the recipe states):
203 g very active starter 100% hydration
253 g all purpose white flour
253 g strong white bread flour
187g eggs - use extra yolk to adjust to this weight
101 g butter
101 g white sugar
91 g water
10 g salt
It takes a couple days to finish these (I start Friday midnight to get Sunday morning donuts) but most of that time is waiting not working).
Couple of notes- he says the final rise takes 12 hours but that must be in a cold climate, here in the subtropics it took about 7 to be perfect. And when he says careful attention to shaping he means it, but it's easy if you keep the dough chilled, with the butter in the dough it's not too sticky. Don't be afraid to really stretch it when forming the little dough balls, you want a tight surface all over. If you can shape buns, and your starter is robust, this is about a foolproof recipe.
https://www.theperfectloaf.com/naturally-leavened-bomboloni-doughnuts/
I can't see the picture in the header, hopefully you can. Will put below too.

I was distracted and so busy when I was your age, no time to slow down. Kids, pets, so much work at my job, never time to think!
Do you exercise? That mental feeling of dissatisfaction can be complicated by physical idleness - I do have to exhaust my body to calm my mind.
Do you have people IRL? Even if you are introverted and asexual you still need a baseline level of community, of people to talk with and be with.
You don't need to achieve anything to be a whole person. I do think your instinct is correct that it's something that doesn't exist because there are so many successful unhappy people, you are outwardly successful already. So maybe you are missing physical activity or social activity.