I don't think it's about any particular diet that works better than another or about that tyrannical word willpower. It sounds overly simplistic to say it's just a decision you have to make based on what you want to achieve, but that's what it is.
You have to really want to lose the weight more than you want the foods that make you fat. When you reach for the snacks, the fatty foods, the sugary stuff, you have to ask yourself, "Do I want this more than I want the weight loss?" If the answer is YES! go ahead, but you won't lose weight. It's pointless to beat yourself up about it. If you really want to lose weight more than you want the extra food, you will cut down and begin to lose weight. You just have to decide. If you are determined, you won't allow others to derail your efforts. Some will try!
From a practical point of view, reducing portion size is a good, easy start.
I recently cut out cakes, chocolate, sweets, biscuits and pastries because of a worrying blood sugar result, and without being hungry, I lost a stone. I wanted to reduce my blood sugar result so much more than I wanted the sweet things!
I can also recommend the 5:2 way of eating because you're only hungry on two days a week rather than every day.