Part of the interview process is finding out how committed you are. A committed person will likely have done plenty of research in order to understand what he is getting into. As this has been done so many times before, I would also say, use the search function.
And polish your shoes.
Edited to add; the interview is not a physical fitness test, it's to see whether you're suitable for the army, or just some walt wasting everybody's time. Have a look at the stickies.