Most ordinary runners are motivated by an individual goal, more than anything: namely, a time they want to beat. As long as he can beat that time, a runner will feel he's accomplished what he set out to do, and if he can't, then he'll feel he hasn't. Even if he doesn't break the time he'd hoped for, as long as he has the sense of satisfaction at having done his very best - and, possibly, having made some significant discovery about himself in the process - then that in itself... is an accomplishment, a positive feeling he can carry over to the net ace.
The same can be said about my profession. In the novelist's profession, as far as I'm concerned, there's no such thing as winning or losing. Maybe numbers of copies sold, awards won, and critics' praise serve as outward standards for accomplishment in literature, but none of them really matter. What's crucial is whether your writing attains the standards you've set for yourself. Failure to reach that bar is not something you can easily explain away. When it comes to other people, you can always come up with a reasonable explanation, but you can't fool yourself. In this sense, writing novels and running full marathons are very much alike. Basically a writer has a quiet, inner motivation, and doesn't seek validation in the outwardly visible.
Haruki Murakami, What I Talk About When I Talk About Running