" For me, running is both exercise and a metaphor. Running day after day, piling up the races, bit by bit I raise the bar, and by clearing each level I elevate myself. At least that’s why I’ve put in the effort day after day: to raise my own level. I’m no great runner, by any means. I’m at an ordinary – or perhaps more like mediocre – level. But that’s not the point. The point is whether or not I improved over yesterday. In long-distance running the only opponent you have to beat is yourself, the way you used to be. "

― Haruki Murakami , What I Talk About When I Talk About Running