Have read all of your posts OP, not read all the replies.
If i was in your position, I would be gentle with myself, I would afford myself the grace that I give other people.
When I make mistakes, I would tell myself that nobody is perfect and making mistakes is ok, I would think what I would say to a friend and say that to myself.
Secondly, I would get outside every single day, whether thats in the garden or a walk.
Thirdly, I would reach out to people, say hello to people I come across, ask about their dog, compliment something I like about them. Only last week, I told a lady in the post office that I adore the character on her top. Reaching out is so good for your social meter.
Fourth, I would look for ways to help other people, doesnt have to be in big ways, but some sort of contribution to your community or neighbours.
Fifth, I would prioritise sleep.
Sixth, I would discover why I eat crap. Do I eat it when I am feeling low, bored, stressed, happy?
All of those things will hugely improve your mental health and help lift you up.
When your mental health is better, you will find the physical stuff easier to do.