" I already had the feeling that the Marines were a world apart, that what we did at OCS would be separate from the rest of my life."
In the text you can read that he is not scared about going into the OCS training but, a bit nervous for all there is to come. Because of all the signs and how the commanders acted, he knew that he was going to go through a lot during his time in the training camp.
In another section he meets Sergeant Olds, and Fick quickly realizes that training is going to be a lot harder. "“Stop eyeballing the freakin’ area, maggot.” My eyes were locked to the front. I didn't think he was talking to me. "
With this quote you can see that Fick is taken aback by the way that the Sergeant is speaking to them, not expecting that tone of voice at such an early stage of training.
Can Nathaniel Fick really make it through the beginning of training in Quantico?