For me it was understanding the idea of equilibrium. The way I use it is to mean the state of something given enough time that highs and lows have evened out.

A practical example is with common diet mentality of dieting until reaching a goal, and then stopping the diet. The diet is a peak, not dieting is a valley, over time youll end up back at the same weight or more. Basically the problem is that modern diets give people high expectations when studies show the most likely scenario is that the weight is lost, and gained back plus some.

So what will work. If we think of this long term equilibrium, the dieting doesnt work because they aren't permanent changes. So if we agree the only way to stay healthy long term is to make permanent changes, we can agree that making cumulative small permanent changes that affect diet will ultimately result in lost weight.

Sugar is the easiest to target IMO. Dairy, meat, and fish also are good things to target too as they cause other health problems besides weight gain. Switching to mainly water is another thing. Even taking on a new hobby or exercising a slight bit more will result in a net loss as less time is able to be spent on eating and more energy is spent physically.

Plant based whole food diets usually result in weight loss because they are less calorie dense, so you will feel full with a fraction of the calories in your stomach. Alternatively you can lose weight with calorie dense foods, but you will likely have to deal with hunger more.

Once I started thinking more like this, it was easier to come up with my own changes rather than shopping around diets with absurd restrictions. You know yourself best, make small changes and keep trending in a good direction, and if you make a "mistake" do your best to forget about it and immediately get back to it.

Not him, but I found my will to lose weight when a close family member was told their liver was failing and they had a few months to live, due to cirrhosis from their obesity. I knew I was on a similar trajectory and my bloodwork showed a hit to my liver function.

Good news is that my relative also found the will to get healthy and their liver improved more than the doctors thought could happen and so we both are doing much better. I'm even under 25 BMI now after losing 40 lbs. Also amazing to be able to move around like I used to as a teenager again.

As to how, not very helpful but just using that fear to drive willpower to just suck it up and eat less and exercise even when I really want to be doing something else. It means to some extent just living with usually being a little hungry and almost never filling full for me. Changed the food for less calorie dense stuff and avoiding refined sugars of course, but still have to reduce food intake.