Genetics

How come we all can't run a 2:15 marathon, or a 4.3 40 yard dash? Genetics, see it's not my fault (thanks mom and dad.) People that train just as hard, if not harder then the elite athletes will fall short of their goal if they don't have the gift of good genes.
So why do we do it? We push ourselves to the limit of break down. For what?
When am out on a long run I ask myself that all the time,( negative Ron ) is it dedication, or foolishness. Nobody makes me get up at 5:00am too do a long run, or train 6 days a week for a marathon that I will be lucky to run in 4 hours.

The only answer I can come up with is internal drive. and that I can thank mom and dad for.