What does Lei Feng mean when he says that I will always be a screw?

This sentence means that I am willing to work hard in an ordinary post and love this job. That is to say, there is a person who has the spirit of screws. The motherland is like a big machine, and we are like small screws on the machine. Although the screws are small, they are very useful. Every screw is indispensable. Do not underestimate yourself.