Sometimes things are more complicated than just wanting it. My family operates a food vending business that has uneven seasonal time commitments. This year during Sep and Oct I was working a lot of 16-18 hour days M-F and 8 hours/day on the weekends. It is very hard to sleep properly and eat a healthy breakfast when doing this and very hard to get in even a couple hours of exercise per week. So I had a bit of a backslide during this 2 month period. However, I still was able to lose 15 pounds from mid-summer to now. I'm working really hard at it now during the slower time. As long as I'm working this type of schedule I just have to get after it harder during the slow times and then allow myself to take a break from weight loss when work takes priority. My goal is just to not backslide this year duing the busy times.
I think I can agree somewhat with the OP, though. You have to want it for yourself, rather than do it because your doctor or your sweetie says they want you to do it. It was the same when I quit smoking. My first 4 attempts failed because I was doing it to please others. The last time I was doing it to please myself and it succeeded.
But again, there are often extenuating circumstances and some people have much bigger hills to climb than others, so there isn't a perfect correlation between desire and results. I don't think it is passing judgement on anyone to say that we could all probably benefit by improving our commitment.