The first part of a diet is the exciting part. You realize you can stay on it, you see results, you have new clothes in a smaller size.
The second part of a diet is the boring part. This is the part that is different for different people, depending on why you lost weight in the first place.
After my third child was born, I wanted to lose weight because I didn't even recognize myself when I saw my reflection in a store window while shopping. When I realized that fat woman was me, I was crushed. I lost about fifty pounds and a year later I lost another 20 pounds. That weight stayed off for seventeen years. After a while, I didn't have to pay attention to what I ate, my weight just stayed the same.
This time when I went on a diet, it was for weight loss and to control my blood sugar. I don't want dialysis, or amputation, or medication. Realizing I was going to be on a diet forever wasn't an immediate thought. I thought, "I'll lose down to what one normal human weighs, then my organs will be able to handle a normal diet with cinnamon rolls and doughnuts."
So day after day, week after week, blah blah...I'm on a low-carb, high fiber diet. That is boring. That's why I am so pleased when I discover recipes that take the boredom out of my diet. I can eat out low carb, but that is boring after a while...meat and something green. Cooking my stuff and controlling what goes in it is more appetizing with more variety.
I'd read about changing how we eat for all time as being the answer to now gaining the weight back. I just put off accepting it as long as I could.