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I believe that your negative attitude is part of what makes this a country of obese, out of shape people. Every form of physical exercise can be made a "sport", and usually is. Yet everyone needs and deserves to exercise. It is none of your business is people who have less running talent than your own (which is nothing special, I might add), choose the potentially healthy challenge of any length of marathon. Running and walking are universal means of human locomotion.
It is also a bizarre logical fallacy to suggest that non-competitive runners somehow impact on the accomplishments of competitive runners. Do playground basketball games "ruin" professional basketball? And also that you seem to endorse pushing to injury even when a major competition is not at stake.
You are essentially saying that people should not train with running unless they meet some arbitrary performance level, which you have somehow set. Or to put it another way, bothering to insult the achievements of others, even if it means cheapening your own achievement.
How ironic, as well, that you choose the example of Oprah for a rather callous and sexist insult, a woman who came quite close to matching your men's time. And I'm sure you ran yours younger, too.
In the end, in your bitterness, it is yourself you belittle. You reduce your own accomplishment from an impressive display of fitness and resolve, to a failed attempt to meet a standard you were genetically inadequate for. That is your choice, I suppose. I make a different choice.