I think that many successful runners approach[ed] running almost entirely as a competitive activity. They try to beat the competition; they aren’t running for health reasons. That might be why it seems, anecdotally, that D1 runners are more likely to quit after college than D3 runners. The D1 runners want to compete at a high level, and when they can’t anymore, they stop. The D3 runners run for fun, so they see no reason to stop.