One skill that separates good ...

One skill that separates good from almost-good runners is an ability to concentrate for an entire race, whether it is a mile or a marathon.
 Kara Goucher

Quotes from the same author

Progress is rarely a straight line. There are always bumps in the road, but you can make the choice to keep looking ahead.
 Kara Goucher
Acknowledge all of your small victories. They will eventually add up to something great.
 Kara Goucher
Do the work. Do the analysis. But feel your run. Feel your race. Feel the joy that is running.
 Kara Goucher
Don't try to rush progress. Remember -- a step forward, no matter how small, is a step in the right direction. Keep believing.
 Kara Goucher
Watching the world's best compete fires you up to achieve your own feats of greatness. When it comes to running, participation and spectating go hand in hand.
 Kara Goucher