Society wouldn't be so obsessed with telling other people what to do if obesity wasn't something that caused a visible change to a person's body. The bottom line? An awful lot of the feigned "concern" about weight loss is driven by people's own selfish desires for people around them to fit a personal preference of what they deem physically attractive.
IMO, so much of this comes down to individuals making personal decisions about lifestyle. Since I know myself better than anyone else, I'll use myself as an example. I think I eat "somewhat healthy". I grew up with a parent who worked in the medical profession and imposed a lot of rules on my eating, growing up. Never had a snack between meals under my parent's roof, for example, and got into the habit of never eating any of those sugary cereals for breakfast ... only the healthy ones like Special K, Product 19, Grape Nuts or Kellogg's "Nutri Grain" products. We always had well balanced meals, even if some of my mom's decisions and beliefs are currently considered wrong. (EG. I remember she avoided avocados, believing they were "too fatty" and therefore bad for you.) But here's the thing. I *also* decided long ago that computers and I.T. was what made me happy and was my career path. That's not very compatible with an "active lifestyle" since you're usually just sitting in front of a screen for 8+ hours a day. I could do what some people do, and go to the gym early in the morning or at night every day or two. But I don't, because it bores me to death and I have so many other things I'd rather do with those hours of my life.
So here I am in my 40's now and surely I could be in better health if that was my primary focus ... but I'm "good enough" to suit me, and IMO, that's ALL that should matter. I'm not the "ideal weight" but I'm not obese either. Last doctor's visit, everything checked out just fine, such as blood pressure. Could stand to have lower HDL levels, I was told, but they weren't horrible. I don't smoke and I don't even drink very often anymore, so I figure I have those things in my favor at least.
It disturbs me when I see other people in a very similar situation to myself, yet they're actually paying doctors to inform them they "need to lose 15 or 20lbs." and they're trying to make all these extra efforts towards that goal. If you didn't already decide for YOURSELF you want to do that, you shouldn't let someone else scare you into doing it now. Nobody ever "got out of life alive" anyway. Live a fulfilling life and live it the way YOU like. It belongs to nobody else but you, and only you can say if making a bunch of changes or compromises in an effort to add a few years onto it is worth it or not. (In my case, it's really not.)