How can you become a healthier version of yourself if you're not willing to question your habits or beliefs and do things differently? Basically, stop being married to what you "do" or "don't do." If you are unhappy with your health (or who you are dating or your job), what you are doing is obviously not helpful or useful!
Everyone has a different potential or ability to change their weight. Of the many aspects of weight management, those that can be modified are exercise, food (portions, type, timing of meals, etc.), relationship with food, stress levels and sleep. Many people forget that all of these influence weight and lifestyle choices -- it is NOT just about food and exercise.
Almost everyone I meet with expresses concerns about their posture. It makes total sense: we all sit way too much, and it is almost impossible to sit for long periods without becoming slightly rounded forward. For most of us some amount of sitting is a necessary evil, but that doesn't mean you can't take steps to mitigate the damages!