Sometimes I think about what kind of reaction I would get if I were somehow able to go back in time and tell George Washington about what I do for a living. How would Moses react to hearing that I make people do hard work an they pay me for it?
Yes, when you think of it on terms like this, it is strange that we exercise at all. Our machines, knowledge of physics, and need for instant gratification have created a world in which many, including myself, require time each day to work our bodies the way they were designed to work. Those who came before us probably never would have dreamed it possible they their children would need more activity that what comes natural each day.
When you look at routine exercise in terms of health improvements, the rewards speak for themselves. Lowered resting heart rate, lowered blood pressure, increased work capacity, increased bone density, increased strength, decreased of injury occurance, improved flexibility, better proprioception, improved aesthetics, and a host of other physical and mental properties. Basically if you are not getting regular exercise then you are robbing yourself of a better life.
I like to think of exercise as an investment in the greatest asset you will ever have: your body. I can't think of anyone who would trade their eyes for any amount of money. No one would trade the ability to walk for a steak dinner or tickets to the Super Bowl. Plenty, though, would trade more years on earth and more time being able-bodied for more time on the couch and more hours at work. "I have no time" is both the oldest and worst excuse. You can tell what is important to a person by how much time is devoted to it. Where a man's treasure is, there his heart will be also.
Whether it be a lot or a little, I encourage you to be a selfish and invest more time in your physical well being. If you don't, some day you'll wish you had!