Of course it’s difficult. Do you think having drive enough to overcome an addiction, or fight to change your situation is simply “easy” if you have discipline? What kind of argument is that? You need discipline precisely because things are difficult, I don’t really see where we disagree on this.
You continue to assume that discipline is something you innately have or don't have as part of your character/soul/whatever you want to call it, independent of your body and brain chemistry, that's where we disagree.
The way people judge "effort" and "difficulty" is broken, that's part of the problem. Whether you have or lack discipline is judged by the outcome, not by the effort that person made because the effort is invisible to the outside world.
Person A quits smoking (with 1 unit of effort), therefore they have "discipline"
Person B fails to quit smoking (with 10 units of effort), therefore they're judged to "lack discipline".
No, Ive never said that discipline is a quality some innately have, and its not what I think.
The problem is with your attempt to grade difficulty here. I dont think, outside of some outliers that are statically insignificant (e.g someone who can kick heroin with no problems or whatever) that the difficulty of getting in shape or quitting smoking is higher for some people than others. It's really difficult for everyone.
I think discipline is probably the wrong term, I guess drive may come closer, but whatever you want to call it, it's a function of your will to change and its a stronger force than any addiction -- clearly, or no one would ever beat any addictions.
This idea of grading and judging people on their 'difficult units' is nonsense, and pushing that as an excuse for people to be helpless is a really harmful narrative to put out there.