As someone who has gained/lost at least 30 stone over the years I feel I can speak from experience. I have tried ALL of the faddy diets.
I have sustained current weight for more than 3 months which is a first for me.
First thing is to think about WHY you want to be healthy and not overweight - my driver is my being healthy for my family. Also, I had a relative with T2 diabetes and watched her lose eyesight and limbs as she refused to look after herself and take it seriously.
The WHY is the most important thing. It cannot be something like a holiday which comes and goes - it needs to be something that is important forever. If you don't have the motivation long term it will go back on - I have proven that numerous times. Find your focus.
Food issues are more complex than eating less/moving more. I still consider myself a fatty and I love food and know every calorie in anything. I just have mental health issues that would require an NHS wait of over 12 months to resolve!
Then tell everyone around you that you are quitting processed foods like cakes/biscuits/chocolate. That way, you know you cannot eat them and you are changing your mindset and telling others your new mindset - they will encourage you (unless they want to saboutage you!).
Then find a form of exercise you enjoy. I walk with friends every day/eve of the week (where possible) for a good natter - usually 1 hr of chat equals 5-6K and it's fun so passes quickly. I have signed up to Les Mills - loads of at home activities for the rainy days.
Accept you will have odd bad days and don't use the excuse of one bad day to have a bad week - as "it's not worth it, I've already failed". Get back on the wagon the next day.
Load your plate with more protein and veg - less carbs. Use My Fitness Pal and log EVERYTHING! Including milk in tea and squash etc. This will help you to manage your inputvs output and get a positive excess daily. Remember it is a marathon not a sprint.
That's all I've got. It may not work for you but find your "forever" goal. You can't do it without genuine motivation that is time restricted. Good luck.