Studies have shown that only certain animals are capable of enjoying the experience of running -- as a behavior to itself. Horses, dogs and men form this elite group. While a large number of human sub-species called "couch potatoes" will deny any of these inherent inclinations, our bodies were designed for endurance traveling. But the rewards for regular exercise are not merely physical -- our minds seem to be quite well programmed for our favorite activity.

The ancient beings who began the evolution of our bodies (and minds) were not able to compete very well for the food supply. Friends of mine who are anthropologists tell me that our ancestors lacked the speed, strength and other physical attributes which helped other animals carve out their niche on the food chain. Eventually, we developed some degree of intelligence which has helped us compete very well (most of the time). But for millions of years the beings who developed these bodies we now inhabit had to cover great distances -- just to find enough of the "scraps" from nature's leftovers to survive. This regular endurance activity developed the cardiovascular bodies and endorphin-receptive minds which we now possess.

While many may want to deny or ignore it, our minds were also programmed for activity. While our bodies evolved into endurance- trained structures, our minds adapted to this regular activity. One might surmise that the endorphins which give us a wonderful relaxation after running were the reward for doing something we needed for survival.

Because running helped human predecessors survive for many millions of years, we may have developed an aversive reaction. Such mental programming is very complex but the pressure of having to do endurance activity for survival could create a negative mental pattern -- similar to job stress. The last thing a bus driver wants to do after a hectic shift in traffic, for example, is to volunteer for carpool duty. So, maybe, the negative reactions to exercise experienced by couch potatoes (and would-be CP's) have a bit of evolution on their side too.

We probably owe our very existence to those ancestors who, in times of famine, trekked on and on until they had gathered enough to live. Fortunately, they also continued moving until they found an environment where the food was available. Today we survive by being creative -- being quickly able to adapt to changes and new opportunities. Running has a hand in this too.

Running stimulates the right brain which can help us to become more creative. When all of the solutions seem to be exhausted, a run will take an edge off the tension and help the right brain search for solutions. Our ancestors had to find them - or die!

When we back away from the obligation and pressure to exercise, there's a wonderful world out there. Very few activities in our modern lifestyle offer such a gentle and convenient way to confront nature and come away the better for it - every time. The basic and simple act of continuously lifting oneself off the earth requires exertion and forces us to pull together our internal resources. Each time we run, we get back to our gut reactions -- and they're often our best. This offers us the opportunity to confront life as it is.

So the internal circuits are there. In some cases, repairs must be made and new wires installed but the infrastructure is in place. When we put it to use regularly, we experience a little bit of true joy.

If your running is not fun, back off, run every other day and slow down significantly to get it back. Who knows...you may be creating more beneficial adaptations to pass on to your descendants.

Olympian Jeff Galloway is the author of Galloway's Book on Running, Return of the Tribes to Peachtree Street, and Marathon! And is a monthly columnist in Runner's World. His low mileage marathon training program is in 30 plus cities in North America.