I've been there. I soooo get it. And as someone who has been there, I'll tell you what I wish someone told me sooner: Try to find some way to get your heart rate up.
It sounds trite, but I swear there's almost no better way to do it. I know how hard it is to start when you're in a rut, but literally, 30 mins of elevated heart rate every day will change things for you. It wont happen immediately, or even over night. But change will come.
I believe in you. The fact that you're posting about it means something.
Anything that you're doing to get out of it? I'm trying hard to learn software dev stuff again from scratch, but watching people work on successful project and low-level languages with ease, while I struggle demotivates me very quickly and I go back to the same cycle.
My problem is a sickness that no doctor can help me with. I have everything set up from moving out and starting university but I just won't get healthy. I fear I might be growing too old also by now. I wish you all the best brother.