David Ricardo

In comparing therefore the value of the same commodity, at different periods of time, the consideration of the comparative skill and intensity of labour, required for that particular commodity, needs scarcely to be attended to, as it operates equally at both periods.

Running taught me valuable lessons. In cross-country competition, training counted more than intrinsic ability, and I could compensate for a lack of natural aptitude with diligence and discipline. I applied this in everything I did.