First up, your book promo selfie is very impressive! I hope I look as good as you do at your age! I'm not as ripped as you are (proof
, since you asked) but I'm fairly happy with myself currently. I eat and drink whatever I want on weekends (last weekend I had rather a lot of red wine on Friday night, an entire pizza to myself on Saturday night, and then another pizza on Monday night, so I'm not exactly some masochistic food nazi), and weekdays I eat whatever I want to, but stay under my energy cap (~6500kj or so). I've just started working out again (20 minutes, 3-4 times a week) after 4 month break thanks to the arrival of our daughter. I think it's fair to say that my approach doesn't take a lot of willpower to maintain a steady weight, and I've maintained this weight for more than three years now so I think it's safe to say it's not temporary.
If your goal is to slowly trim 12kg over the course of several years (if I'm rightly interpreting your blog post), then eating a healthy diet and exercising six hours a week will obviously do the trick. However, my post was in the context of people who need to "lose a lot of weight". To do that you need to run a significant energy deficit - ~2500kJ a day seems to be a good target. I challenge you to suggest a diet that will allow you to run that kind of deficit without feeling hungry (and thus, requiring willpower). And not just a diet where you don't want to eat more broccoli, but one where you won't be tempted by the chips at the lunch bar. I can have those chips if I want 'em, as long as I don't go over my cap.
Obesity rates in many first-world countries are due, I believe, to poor health and nutritional education (just witness the flood of replies I've had in this thread saying either "energy balance doesn't affect weight gain/loss" or "energy balance is out of my control") compounded by food that is super tasty but very energy dense and very nutritionally poor, and by food manufacturers pushing ever-bigger portions in a runaway arms race against each other.