This describes my experience well, but I think it is worth pointing out that what I (and I can only describe myself here because I don't want to assume you are

This describes my experience well, but I think it is worth pointing out that what I (and I can only describe myself here because I don't want to assume you are the same) have could be described as mild depression. What the OP describes would be, I assume, described clinically as severe depression. I have been able to "self medicate" like you with exercise, diet, rigorous organizing and planning tools, and other ways of "ignoring" what my brain tells me to do. When I was younger, I was briefly on medication and did not like the side effects, and I have been lucky enough to be able to cope with the tools I have at my disposal. I do not believe this is possible for people with severe depression, and highly encourage them to seek professional help.