My approach is different. It's about creating certain habits that address the issue so your body wants to be thin. Then it requires no discipline at all. I will go on record saying this, and I've said it many times: Once your body wants to be thin (though it can be easy or hard to get to that point), it is effortless to lose weight.
So even though humans cannot (yet) choose or alter their genetic coding, we are (except in a few extreme instances) able to decide what we want to do with that coding. So do we give in to every little impulse? Or do we place value on more than just what seems fun and interesting in the moment? Despite genetic predispositions, the choice is ours to make.