Nope. We're using more of our genetic potential than the average guy, but 'tougher' no. Which is why we're sometime surprised when people off the street with only months of training in a physical activity similar to ours, begin to outperform us in spite of our years of training, whether running or biking. Which is why that huge person on the street may actually have greater heart and lung capacity than us, plus the ability to endure greater suffering in life or on a bike, just happenned to abuse self or just not contain themselves, and put on the extra 50 or so pounds.
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