I'm one of the poster-children for improved lifestyle effects. I wasn't too bad off, but I'm 6'2" and was 270 at my heaviest. Had hypertension, bad cholesterol, aching knees, blah blah blah
I needed to be under 200lbs to race motorcycles. I started running, eating right (another shout out to the "no deep-fried foods" crowd)..and started doing things I only dreamed about. I stopped in at a local boxing gym after reading an article in the local fishpaper, fast-forward two years and I'm fighting veteran class in Golden Gloves / USA Boxing. Also doing any triathlon that fits my schedule, I've always loved swimming. Last summer I had a bit of a problem with not eating enough, and I started going into regular ketosis. Was down to 170lbs and @ 6'2" with a large frame, I looked pretty sick.
You'd be surprised what happens when you get yourself into shape - knees start working correctly as they get strong..all the other plethora of ailments I had just disappeared. The only exception was the hypertension - that turned out to be hereditary.
But yeah, when I see other people in the same place I was, and worse, I feel horrible because past poor eating habits/sedentary lifestyle...it's a choice. Most people choose to be like that - as someone else posted, it's no different than alcohol or drugs - a slow suicide.
FAT Stimpy451 circa 2005 - ~270lbs and really bad long hair braid
Smaller Stimpy451 with stepdaughter ~175lbs 2009