You're clearly depressed. Ennui is a pretty common symptom, it pretty much means you don't really care about anything. The best thing to do is just force yourself to exercise, and start acting on more whims imo. You need something to work toward in order for your life to not feel totally pointless regardless of what it is. For a lot of people that's their career, their partner, or hobbies. Consider picking up a skill you've always admired, just work a little on it everyday so you have something to do that feels like it's actually progressing you as a person, this can reduce your self loathing. Also I'd talk to a doctor about it if you've been feeling this way for years.
If they tell you to take anti-depressants go to therapy first.
E: Depression is episodic, you'll probably feel better eventually, but you gotta make some effort. Doing literally anything will suck for a while, but it's worth doing something. Going to therapy sounds like hell, and is really nerve wracking, but they've seen much crazier people than you, and whatever drove you to even post about this is practically begging for someone to talk to about it.