How can I tell the bully in my brain to scram?

I get up most mornings and run/swim/spin before work, and have done for years.

This is what works for me: Make the decision the previous evening. Tomorrow I am going to get up at x time and do x thing.
Ok. Sort out the logistics - I have to lay out the kit so not digging around while partner is asleep. All required clothes for workout and then clothes/wash bag etc for after ready to go.
Make lunch/breakfast so they just need to come out of the fridge and are ready to be packed.

Alarm goes off - get up. No procrastinating. No its raining, I'm tired, I'll do it later, 10 more mins etc. I have to just get up and get on with it. As soon as I am having that debate in my head I won't do it.
It has to be discipline in the same way I do the housework. I don't want to clean the bathroom either, I still have to get on with it. I also know that as soon as I have got going I will be fine. Its just that hauling self out of bed bit that's tricky

You can change thought patterns, takes some time but is possible. I've had to work on it for a long time. Try having a look at CBT techniques. You can make a plan which involves small changes to habits and just work your way along....

I would start with baby steps. You aren't just going to become this super awesome fit person overnight. Your exercise doesn't have to be high impact or strenuous...in fact, anything like that should be undertaken after building up a good base level of fitness, and even then those things should be side dish and not the main course of your fitness regimen. I started out just walking and took things from there as I built my fitness up. Going from nothing to full throttle out of the gate is only going to burn you out and increase your risk of injury. Go slow...build up. Same with dietary changes...doing a complete 180 with your diet is likely not to work or help you build any kind of consistency. Make small change and set reasonable goals for making those changes.

Also, play with timing of your exercise. I'm not a morning person and the most rigorous thing I can do in the early morning is take my dog for a leisurely walk while I drink my morning coffee and clear the cobwebs. I do most of my exercise during my lunch hour at work which is when I feel the best and it's also just a really nice way to break up the day.

That's a hard one. I amy worst enemy. I find it if I get a private journal of things I did a great job of. For example I worked out when I felt like taking a nap instead. Write 3 things a day about you. I bet you will find out that you rock more than you think.7

I struggle with working out in the morning, too. I regularly work out at lunchtime or after work. There's nothing wrong with that!

However, when I work out in the morning, it gives me an extra confidence boost. So, I often attempt it. Sometimes, I am victorious!

I have sometimes conquered my morning workout by the following techniques.

1) On a day off work when you have few other pressures, get up and do something active before you eat breakfast. Doesn't matter how long it takes or what it is (e.g., a walk outside), just delay breakfast until afterward. Breakfast will be your reward!

2) On a work day, do something active before you have your coffee, even if it's just walking around the block. Bring your coffee with you, if you want.

3) Join an exercise group that meets in the morning. Nothing harder than you can manage. Something you find fun.

In all cases, lay everything out the night before, skip the booze, get to bed early, and pick your wake-up time. I find it helps to put on the bluetooth headphones right when I get out of bed and listen to music to wake up. The sooner you are on the other side of the door, the sooner you will wake up and feel normal.

There’s a lot going on in your post. Setting out to fix “loser” probably won’t get you far. Its too big and too vague. As others have suggested, try to break things down into smaller pieces. Try this-

1 You want to exercise regularly. (It’s overrated for weight loss but it can really do a lot for our brains, especially fighting depression.)
2 You want to lose weight.
3 You want to push back against negative thinking.

How does that look to you? Let’s work backwards. Fact is we can’t shut off our brains, we aren’t wired like that. I’ve lost a lot of weight and have maintained for years. I also went from couch potato to gym regular. But my brain still has a collection of old junk its willing to drag out on a moments notice. Especially when I’m tired. One of the things I’ve done is listen to positive affirmations on YouTube. Another is to make sticky notes with positive words and phrases and stick them where I will see them. Sound silly? Both those things helped. Its a fact that the voice in our head can’t say 2 things at once. If it is saying something positive, even if it’s forced to, it can’t be saying something negative. Try it. You’ll see that a lot of what we call negative thinking, isn’t thinking at all, it’s just a bad habit. Habits can be changed.

If you want to lose weight, try calorie counting. Its a whole set of things to do and it works.

You don’t say but do you walk your best dog buddy in the morning? Instead of bouncing out of bed for a high impact workout, what if you just got up and went for a walk? You can add to it later after you are in the habit of getting up to exercise. I wanted to be the kind of person who worked out regularly. I came home from work, put on my shorts and T shirt and headed for the exercise bike that I knew we had in the basement. I found it in the corner, took the stuff off of it and put it in front of the TV. That first day I did 8 minutes, that was the most I could do. 8 minutes. That was about 28 years ago. Yesterday I trained with weights for an hour, walked for an hour and played Pickleball
for 1 1/2 hrs. All that from 8 minutes on a stationary bike.

You can do this. I can tell you for a fact because I did it and there’s nothing special about me. I’m just likely more stubborn than a lot of people. Someone on here said something about baby steps, its true. And we had to crawl before that. If you can make just one positive move per day, no matter how small, that will be 7 things in a week, 30 things in a month. Its mostly a matter of problem solving and persistence. Never quit.