A lot of people are their own enemies. They regard themselves as unlikely to succeed in college and often feel that there have been no accomplishments in their lives. In my first year of college especially, I saw people get themselves down all too quickly. There were two students in my class who failed the first test and seemed to give up immediately. From that day on, they walked into the classroom carrying defeat on their shoulders the way other students carried textbooks under their arms. Both students hang on until about mid-term. When they disappeared for good, no one took much notice, for they had already disappeared in spirit after that first test. They are not the only people in whom I have seen the self-doubt do its work. I have really wanted to shake them by the shoulders and say: "You are not dead. Be proud and pleased that you have brought yourself here to college. Be someone. Breathe. Hope. Act. " Such people should not use self-doubts as an excuse for not trying. They should pull themselves together and get to work. They should start taking notes in class and trying to learn. Above all, they should not give up without even trying.
The underlined phrase "get themselves down" (Para. 1 ) probably means______.

A. tell lies
B. lose confidence
C. avoid dangers
D. waste time