Found this on a website. John Bingham is a runner who evangelizes the art of running for its own sake.
Why It's Worth The Effort
MOST OF THE CHANGES that a more active lifestyle brings are invisible. Sure, in time you may find that your clothes fit a little differently. If you are new to running, you may find that a distance that once seemed impossible now seems easy. If you are more experienced, you may find that your long runs and speed work are yielding tangible results.
But these changes are not the ones that are the most important. The changes that matter most are the ones going on inside, where you can’t see them. I'm not talking about the subtle increases in the strength of your heart or lungs or legs. I'm talking about the very real changes in the strength of your resolve and your spirit.
Each day that you invest in yourself, you are becoming more of what you want to be. By giving yourself permission to dream of new PRs or completing a 5K, you are making sure that there is hope in your life. Instead of looking backwards to the good old days, you are assuring yourself that the best is yet to come.
At the heart of the matter, the real changes are in how you think about yourself. By discovering your limitations and then overcoming them, you can learn to be your own hero. And that, for most of us, is the biggest change of all.