If work was fun they wouldn’t have to pay you to do it.
I used to be like you. Petrified by the idea of working in a job I hated for the rest of my life. Positive I would die old and miserable. Had some pretty crippling depression because of it. I was positive I would hate every job because there was nothing I wanted to do. I needed a job though, and one with health insurance and benefits. So I joined the military. You know what? I absolutely hated my first career path. I was every bit as miserable as I thought I would be. Things were actually worse for me than when I was unemployed, depression wise.
It got me focused though. I realized that I needed to get my stuff together and figure out something that I could tolerate doing for the next 20 years. Yeah, tolerate. Very, very few people get to do something they are passionate about, and no one loves their job every single time they go to work. For me it was finding something that challenged me mentally. Language acquisition and translation work. (I am still in the military, BTW. That wasn’t the part of my job that I hated. Fixing aircraft was the part I hated.)
Figure out something you can tolerate doing for 20-30 years, because it really is worth it. 8 hours a day still leaves a lot of time to ride, have hobbies, have relationships, and generally enjoy life. Here is another secret. Money doesn’t buy happiness, but it sure as hell lays the foundation for a happy life. Not having to worry about paying your bills or what’s going to happen if you’re in an accident gives you the peace of mind and freedom to enjoy your downtime.
No one should work at a job they hate, but there is a pretty big stretch of land between hate and love. Find something in the middle and go for it. Give up horses, don’t give up horses, that part is up to you, but find yourself a job that will give you the base you need to be able to make that choice.