How can you possibly ever know how far or fast you can go if you've never run all-out?

Buddhism Day by Day

Wisdom for Modern Life by Daisaku Ikeda
Saturday, July 13, 2013:

 

People shouldn't hesitate to exert their all, in a way true to themselves. How can you possibly ever know how far or fast you can go if you've never run all-out? To give up even before you've tried is actually arrogance—an affront to the wondrous power of life within you and disrespectful to yourself. It is cowardly.