Reasons Why #4: Numb ass.
I work a very sedentary job. I sit at a computer pretty much all day, every day. Even moreso now that I work from home and don't have the occasioanl trip to the cafeteria to break up the monotony of sitting in my chair.
This is both a reason why I am fat (I gained a lot of weight when I started working full time) and a reason why I need to not be fat. Because by the end of the day, my ass gets numb. And when your ass is as large as mine, that's a lot of numb.