You have to ditch this:

I'm also overweight and can't be arsed to work out. I have no semblance of motivation to do much of anything. I always think and plan to do something like ride our exercise machine, but then I never do it.

From your post, it seems like you are constantly relating to past events and how history has evolved. I get it.

You need to let go of the past.

You need to stop always seeing yourself as that heavy person that cannot lose weight. Your first run doesn't need to be 5 miles, and it actually doesn't need to be a run at all. Or a jog. Or 5 miles. Start by walking a quarter-mile outside of your neighborhood. No more. No less. A single, quarter-mile. Afterwards, treat yourself to one of your favorite meals. But you better do that quarter-mile before having that meal, and you better do it the next day and make it a half-mile the next week. Gradually build on it man, and you don't have to stop doing the things "you enjoy doing." If you want a burger, then have a burger. But you MUST take care of yourself. Don't do this to look good for others or be validated etc. Do this because it is healthier for your body in the short-run and the long-run. You will be a happier person.

I know this is hard, but don't be too hard on yourself. I know that's cliche, and I myself hate hearing shit like that...but I'm going to ask you a question...Is it worth it?

I want you to ask yourself that question again...Is it worth it? Is it worth what you "gain" from letting the dishes pile up and fruit flies start to buzz around your sink? Is it worth the "effort" you saved by letting that extra dish pile up? Is it worth the depression you're feeling now?

It's a cheesy-ass line from a horrible actor from a movie I never saw, but I'll leave you with this... In life, it's not about how hard you hit. It's about how hard you can get hit and keep moving forward. If you know what you're worth, then go out and get what you're worth, but you have to be willing to take the hits.

Is it worth it?

Those dishes aren't going to clean themselves, and what's happened to you in the past isn't going to clean them either. Clean the dishes and you'll be happier...I guarantee it.

That's what I wanted to add here and I hope it helps you. Living in the darkness sucks, but I'm going to tell you...Life is going to keep moving with or without you. I wish I could tell you why some things happen the way they do in this world...but I can't. I've just learned, and it's something I'm still trying to teach myself everyday, but you have to keep moving.