In team sports the athletes ...

In team sports the athletes were bonded by each other, there was an immense peer pressure to keep going. One dared not miss a practice for fear of letting his teammates down. Every time an athlete thought of getting back into bed in the morning he knew he would have to face the anger of his closest friends. But the sculler had to find motivation entirely within himself. No one else cared.
 David Halberstam

Quotes from the same author

QUESTION: Do you know what the greatest test is? ANSWER:Do you still get excited about what you do when you get up in the morning?
 David Halberstam
During their college years the oarsmen put in terrbily long hours, often showing up at the boathouse at 6:00am for preclass practices. Both physically and psychologically, they were separated from their classmates. Events that seemed earth-shattering to them-- for example, who was demoted from the varsity to the junior varsity -- went almost unnoticed by the rest of the students. In many ways they were like combat veterans coming back from a small, bitter and distant war, able to talk only to other veterans.
 David Halberstam
Rowing, particularly sculling, inflicts on the individual in every race a level of pain associated with few other sports. There was certainly pain in football during a head-on collision, pain in other sports on the occasion of a serious injury. That was more the threat of pain; in rowing there was the absolute guarantee of it every time.
 David Halberstam