Why Do We Hurt Ourselves?

When i was @ other schools we didn't get detention for not doing our home work. it just effected our grades really badly. I would never do my homework, but pass all the tests we took. in the end i still got a bad grade and had to go to summer school. thats one way i hurt myself badly.
For students who dont want to "hurt" themselves just do/turn in all your work. Be it homework or classwork, just dont fall behind on it. Even if it is late turn it i. i mean 5 points out of 10 points is better than 0 points.
The letter Mr. Hsu sent out really made sense to me. and it was true for alot of people including my self. i know i used to do the same thind when i was in middle school. I agree with what he said because it relates to many different people on so many different levels.