I am a true believer in behaviour modification...one tiny little thing at a time. I do not believe that we can maintain huge, drastic changes in our lifestyle over long periods of time...so I do everything with moderation and over time.
First I switched out all 'whites' for darks...White flour became whole grain, bran or other similar types (I no longer enjoy white bread of any kind any more), then I limited it to only certain days of the week...I give myself 1 bread/carb day/week...so there is no frustration...White sugar became dark or none at all (I avoid the artificial sweetners most of the time and only drink occasional diet sodas), plain 2% yoghurt instead of sugary stuff (no sweetner please, it fools the pancreas but can hurt you in the long run)...learned to eat salads with just lemon and olive oil + spices instead of gobs of dressing and only grill, broil or barbque most meats.
I am very active physically (don't own a car, walk everywhere or take public transportation which mean stairs and long corridors), carry my groceries miles and generally act as if I live in 1950...I exercise too but my activity level is probably higher than most people's exercise level so I can enjoy my exercise without stress.
Not buying a lot of junk helps too...if I don't have it I can't eat it.
For me it is a a case of balance...As my surgeon says, Life is all about intake and output...less intake (calories) and more output (exercise, sports...) and you lose weight, more intake and less output and you gain (metabolism is the only variable)...your body will plateau at some point and you will have to up your game to kick the metabolism up and make it burn more...
I've finally cut out the caramel corn, nuts and ice cream...so I am seeing results without much effort...sometimes you just have to choose a food and remove it from your diet as if you were alergic to it (alcohol, chips, pizza...) and find a replacement for it...you will see a gradual difference but that is the best kind.