If I had to pick one thing, it'd be my weight. I've lost 150lbs and have been keeping it off for years. People who've never lost a significant amount of weight (north of 50lbs) probably can't understand what it is like to have to fight your body every day of your life. I have to avoid temptation as much as possible, which means keeping only enough food in the house to survive for a week and avoiding social functions, among other things. If I know there's food somewhere nearby, I'll be distracted thinking about it until I either eat it or go somewhere else. I have to meticulously track my caloric intake and keep it under 1600/day average just to maintain, even with 6+ hours of the gym each week. They never tell you that part about losing weight, that the damage to your metabolism is already done and will never function normally again.
Do you have any idea what it is like to be compelled to eat? To be unable to stop yourself? to hate that you can't stop yourself? I'm going to guess not, it's awful. And you know what the worst part of it is? How easy everyone seems to think it is. Oh, you're having trouble with overeating? Here, let me parrot some bullshit clickbait nonsense from the internet.