thanks for this post. I do relate to what you write. Like you, I also reached many goals in life that others find impossible, BUT never got to manage something "simple" as my weight.
I have been overweight, up to mildly obese, half of my life (the second half); as a kid, just like you.
Now, you are asking what is the magic formula. I can tell you that now I am like many other enthusiasts in the forum, I found IT and it's magic because it fits me. I believe that every diet works: Dukan, Atkins, metabolic balance (popular in Germany), South beach, cabbage soup, you name it, all of those work to lose weight, and worked with me, too. Up to when I lost interest.
It turns out that what I needed were three things:
1) motivation - the same kind that get me through my other goals - something that resonates deep down.
2) a wake up call, in my case it was seeing me in a picture taken by someone else without me knowing. Somehow, even though I knew I was overweight, till that moment I did not see it (LOL: it is a bit like those girls who are thin and see themselves fat in the mirror, but the other way around).
3) a plan that I knew, again, deep down, it could work with my lifestyle. Because I like my lifestyle and while I can modify it temporarily to follow a diet, in the very end I want to keep it; I now know that it will not work with other diets than 5:2 (or fasting based diets in general).
I am now losing the weight (-10Kg in three months), I should reach my goal in time for my 50th birthday (I need to lose 20, ideally 25 kg, not little) next year and I am already seeing how this will eventually work lifelong.
So, my advice to you is: find what is right for you, something that is not a miracle diet (20 Kg in 20 days sort of thing) but a miracle eating plan that fits your lifestyle and resonate with you. All the other, it is my experience and I gather of many others in the forum, will work, sure, but only temporarily.