I like to pick up the Men's Health Magazine every once in a while when I'm grocery shopping. I did so just this morning and I was reading an article about the proper breakfast food choices. Apparently, many men have been making improper choices for breakfast. They tend to eat high carbohydrate meals that leave them hungry before long and they end up eating more calories throughout the day. The solution is to eat a breakfast with a better balance of proteins and fats. They even included some recipes of goofy food combinations that I'd never eat for breakfast (gotta have something new, don't you?).
It was interesting, it didn't tell me anything that I didn't already know. I don't eat a high carb breakfast. I typically like to strike a balance between calorie content from carbs, fats, and proteins. I didn't need to read an expert's advice to figure this out. I learned by eating and recognizing what made me feel good and what didn't. It was barely a conscious decision. Apparently, it's not for others.
That's a problem. Based on my experiences, when I'm physically active, I can tell what I should be and shouldn't be eating. When I backpacked the Grand Canyon, my staple snack was a combination of dates and nuts with lots of water. I figured out fast that the date's high sugar content would get me going quick (I later learned that they are high in fast-absorbed glucose) but wouldn't sustain me. The nut's high fat content would. Most people don't do much in the way of physical work, and they are incapable of figuring out that their food selection is bad.
If anything, they are suffering from a lack of a good mind-body connection. In a perfect world, your body should tell your mind what does and doesn't work for food. Your mind in turn, well, does or doesn't desire to eat it. If everything is clicking, then you'll feel energetic and youthful. Proper exercise does this.
Now, I said PROPER exercise. There's definitely exercise that won't promote a good mind-body connection. In that Same Men's Health Issue, they showed a man my age who used to lift weights and drink heavily on the weekend. He was 35 pounds overweight. Only when he went hiking in Brazil did he notice the error of his ways and adjusted his lifestyle accordingly.
This is the reason why good, knowledgeable men like John Peterson encourage you to become masters of yourself. If you don't establish this kind of self mastery, you'll be at the mercy of science to catch up with something that you could reason for yourself even if you don't know why. If your exercise routine doesn't build up your mind-body connection and make you the master of yourself, you're not getting the full benefits of what exercise can do for you.