To be perfectly honest, the reason I personally don't exercise is due to 2 reasons:
One, I don't care.
Two, because my ego is pretty insane as it is, but still kept somewhat in moderate control. If I had a glorious six-pack, bulging biceps, and essentially a bod like an Adonis, there'd really be no stopping my ego. The flexing, the kissing of the biceps, and so on. The double sterotypical whammy of the Black & Italian in me would just have a tank top field day with it.
Got nothing to do with either, really. The Adonis bod is something so ridiculously hard to achieve. I know a guy who went all the way, spent a horrible amount of money in proteins and weights, completely got obcessed with his body, and exercised an amazing amount of hours every single day. This went on for years. His arms certainly got a bit bigger, but he didn't look different at all. When he flexed, I went "Oh, he's not that skinny anymore", but after that, he might have been the most physically fit person I knew, but he didn't look a wee bit different. Most stuff about your body is sadly genetic. You won't become Flex Mentallo if you start doing a daily exercise. The objective isn't that, and was never that. The amount of training to achieve a status you're talking about is ridiculous.
I'm just talking about leading a healthy lifestyle. Being able to do ALOT more things without getting tired. Looking the same as you get older. Being able to defend yourself if necessary. Feeling better, not about your body, buy overall better, happier and with the right chemicals going through you and not worrying about beer bellies or bad skin. Your day will seem like it has more hours, you'll gain more vitality and will be hungrier and more alert in general. Your senses themselves will feel like they're improved. Even your memory will be better. Feel like working a longer day? You won't feel tired about it. Any frustrations you have will either disappear or be easier to handle. And your mind in general will feel clearer.
Heck, the reason I exercise isn't even any of those, but I do welcome them. The reason I do, is so as I get older, I don't lose any of my faculties. So my memory stays the same, so I'm able to work as many hours as I do today, so I don't have to feel as if I'm getting more and more frail or tired, or more forgetful as I go. I already had a great self-esteem back when I didn't lift a muscle, it's not that. It's having a longer longevity of all things in general. Never feeling useless at anything, no matter how things go.
BTW, look like Genndy's moving to Sony Pictures Entertainment. As long as they give him a lead position and let him do his stuff, good for him.
http://animationguildblog.blogspot.com/2011/03/network-of-cartoons.html