I'm writing a war sci-fi novel. At the start of the novel, my MC really wants to get into a particular unit, let's call it Space-Marines. His struggle through the training serves to showcase his high motivation, the fact that the soldiers are prepared as well as they can possibly be before being sent off, it lets me set up the character as he was before combat, and more. This later allows me to go on and do to the character everything war can do to a man.
The trouble is, while during training the MC has a clear goal, and struggles to attain it, his success is a foregone conclusion: of course he'll end up in the unit he wants. Otherwise, there won't be a story.
How do I avoid this first part becoming boring to the reader due to its foregone conclusion?
I specifically do not want to just skip it and start, like All Quiet on the Western Front, with the soldiers already at the front and jaded. I want to show "the boy next door" getting to that point.